python模块：pickle

 """Create portable serialized representations of Python objects.

 See module copyreg for a mechanism for registering custom picklers.
 See module pickletools source for extensive comments.

 Classes:

     Pickler
     Unpickler

 Functions:

     dump(object, file)
     dumps(object) -> string
     load(file) -> object
     loads(string) -> object

 Misc variables:

     __version__
     format_version
     compatible_formats

 """

 from types import FunctionType
 from copyreg import dispatch_table
 from copyreg import _extension_registry, _inverted_registry, _extension_cache
 from itertools import islice
 from functools import partial
 import sys
 from sys import maxsize
 from struct import pack, unpack
 import re
 import io
 import codecs
 import _compat_pickle

 __all__ = ["PickleError", "PicklingError", "UnpicklingError", "Pickler",
            "Unpickler", "dump", "dumps", "load", "loads"]

 # Shortcut for use in isinstance testing
 bytes_types = (bytes, bytearray)

 # These are purely informational; no code uses these.
 format_version = "4.0"                  # File format version we write
 compatible_formats = ["1.0",            # Original protocol 0
                       "1.1",            # Protocol 0 with INST added
                       "1.2",            # Original protocol 1
                       "1.3",            # Protocol 1 with BINFLOAT added
                       "2.0",            # Protocol 2
                       "3.0",            # Protocol 3
                       "4.0",            # Protocol 4
                       ]                 # Old format versions we can read

 # This is the highest protocol number we know how to read.
 HIGHEST_PROTOCOL = 4

 # The protocol we write by default.  May be less than HIGHEST_PROTOCOL.
 # We intentionally write a protocol that Python 2.x cannot read;
 # there are too many issues with that.
 DEFAULT_PROTOCOL = 3

 class PickleError(Exception):
     """A common base class for the other pickling exceptions."""
     pass

 class PicklingError(PickleError):
     """This exception is raised when an unpicklable object is passed to the
     dump() method.

     """
     pass

 class UnpicklingError(PickleError):
     """This exception is raised when there is a problem unpickling an object,
     such as a security violation.

     Note that other exceptions may also be raised during unpickling, including
     (but not necessarily limited to) AttributeError, EOFError, ImportError,
     and IndexError.

     """
     pass

 # An instance of _Stop is raised by Unpickler.load_stop() in response to
 # the STOP opcode, passing the object that is the result of unpickling.
 class _Stop(Exception):
     def __init__(self, value):
         self.value = value

 # Jython has PyStringMap; it's a dict subclass with string keys
 try:
     from org.python.core import PyStringMap
 except ImportError:
     PyStringMap = None

 # Pickle opcodes.  See pickletools.py for extensive docs.  The listing
 # here is in kind-of alphabetical order of 1-character pickle code.
 # pickletools groups them by purpose.

 MARK           = b'('   # push special markobject on stack
 STOP           = b'.'   # every pickle ends with STOP
 POP            = b''   # discard topmost stack item
 POP_MARK       = b''   # discard stack top through topmost markobject
 DUP            = b''   # duplicate top stack item
 FLOAT          = b'F'   # push float object; decimal string argument
 INT            = b'I'   # push integer or bool; decimal string argument
 BININT         = b'J'   # push four-byte signed int
 BININT1        = b'K'   # push 1-byte unsigned int
 LONG           = b'L'   # push long; decimal string argument
 BININT2        = b'M'   # push 2-byte unsigned int
 NONE           = b'N'   # push None
 PERSID         = b'P'   # push persistent object; id is taken from string arg
 BINPERSID      = b'Q'   #  "       "         "  ;  "  "   "     "  stack
 REDUCE         = b'R'   # apply callable to argtuple, both on stack
 STRING         = b'S'   # push string; NL-terminated string argument
 BINSTRING      = b'T'   # push string; counted binary string argument
 SHORT_BINSTRING= b'U'   #  "     "   ;    "      "       "      " < 256 bytes
 UNICODE        = b'V'   # push Unicode string; raw-unicode-escaped'd argument
 BINUNICODE     = b'X'   #   "     "       "  ; counted UTF-8 string argument
 APPEND         = b'a'   # append stack top to list below it
 BUILD          = b'b'   # call __setstate__ or __dict__.update()
 GLOBAL         = b'c'   # push self.find_class(modname, name); 2 string args
 DICT           = b'd'   # build a dict from stack items
 EMPTY_DICT     = b'}'   # push empty dict
 APPENDS        = b'e'   # extend list on stack by topmost stack slice
 GET            = b'g'   # push item from memo on stack; index is string arg
 BINGET         = b'h'   #   "    "    "    "   "   "  ;   "    " 1-byte arg
 INST           = b'i'   # build & push class instance
 LONG_BINGET    = b'j'   # push item from memo on stack; index is 4-byte arg
 LIST           = b'l'   # build list from topmost stack items
 EMPTY_LIST     = b']'   # push empty list
 OBJ            = b'o'   # build & push class instance
 PUT            = b'p'   # store stack top in memo; index is string arg
 BINPUT         = b'q'   #   "     "    "   "   " ;   "    " 1-byte arg
 LONG_BINPUT    = b'r'   #   "     "    "   "   " ;   "    " 4-byte arg
 SETITEM        = b's'   # add key+value pair to dict
 TUPLE          = b't'   # build tuple from topmost stack items
 EMPTY_TUPLE    = b')'   # push empty tuple
 SETITEMS       = b'u'   # modify dict by adding topmost key+value pairs
 BINFLOAT       = b'G'   # push float; arg is 8-byte float encoding

 TRUE           = b'I01\n'  # not an opcode; see INT docs in pickletools.py
 FALSE          = b'I00\n'  # not an opcode; see INT docs in pickletools.py

 # Protocol 2

 PROTO          = b'\x80'  # identify pickle protocol
 NEWOBJ         = b'\x81'  # build object by applying cls.__new__ to argtuple
 EXT1           = b'\x82'  # push object from extension registry; 1-byte index
 EXT2           = b'\x83'  # ditto, but 2-byte index
 EXT4           = b'\x84'  # ditto, but 4-byte index
 TUPLE1         = b'\x85'  # build 1-tuple from stack top
 TUPLE2         = b'\x86'  # build 2-tuple from two topmost stack items
 TUPLE3         = b'\x87'  # build 3-tuple from three topmost stack items
 NEWTRUE        = b'\x88'  # push True
 NEWFALSE       = b'\x89'  # push False
 LONG1          = b'\x8a'  # push long from < 256 bytes
 LONG4          = b'\x8b'  # push really big long

 _tuplesize2code = [EMPTY_TUPLE, TUPLE1, TUPLE2, TUPLE3]

 # Protocol 3 (Python 3.x)

 BINBYTES       = b'B'   # push bytes; counted binary string argument
 SHORT_BINBYTES = b'C'   #  "     "   ;    "      "       "      " < 256 bytes

 # Protocol 4
 SHORT_BINUNICODE = b'\x8c'  # push short string; UTF-8 length < 256 bytes
 BINUNICODE8      = b'\x8d'  # push very long string
 BINBYTES8        = b'\x8e'  # push very long bytes string
 EMPTY_SET        = b'\x8f'  # push empty set on the stack
 ADDITEMS         = b'\x90'  # modify set by adding topmost stack items
 FROZENSET        = b'\x91'  # build frozenset from topmost stack items
 NEWOBJ_EX        = b'\x92'  # like NEWOBJ but work with keyword only arguments
 STACK_GLOBAL     = b'\x93'  # same as GLOBAL but using names on the stacks
 MEMOIZE          = b'\x94'  # store top of the stack in memo
 FRAME            = b'\x95'  # indicate the beginning of a new frame

 __all__.extend([x for x in dir() if re.match("[A-Z][A-Z0-9_]+$", x)])

 class _Framer:

     _FRAME_SIZE_TARGET = 64 * 1024

     def __init__(self, file_write):
         self.file_write = file_write
         self.current_frame = None

     def start_framing(self):
         self.current_frame = io.BytesIO()

     def end_framing(self):
         if self.current_frame and self.current_frame.tell() > 0:
             self.commit_frame(force=True)
             self.current_frame = None

     def commit_frame(self, force=False):
         if self.current_frame:
             f = self.current_frame
             if f.tell() >= self._FRAME_SIZE_TARGET or force:
                 with f.getbuffer() as data:
                     n = len(data)
                     write = self.file_write
                     write(FRAME)
                     write(pack("<Q", n))
                     write(data)
                 f.seek(0)
                 f.truncate()

     def write(self, data):
         if self.current_frame:
             return self.current_frame.write(data)
         else:
             return self.file_write(data)

 class _Unframer:

     def __init__(self, file_read, file_readline, file_tell=None):
         self.file_read = file_read
         self.file_readline = file_readline
         self.current_frame = None

     def read(self, n):
         if self.current_frame:
             data = self.current_frame.read(n)
             if not data and n != 0:
                 self.current_frame = None
                 return self.file_read(n)
             if len(data) < n:
                 raise UnpicklingError(
                     "pickle exhausted before end of frame")
             return data
         else:
             return self.file_read(n)

     def readline(self):
         if self.current_frame:
             data = self.current_frame.readline()
             if not data:
                 self.current_frame = None
                 return self.file_readline()
             if data[-1] != b'\n'[0]:
                 raise UnpicklingError(
                     "pickle exhausted before end of frame")
             return data
         else:
             return self.file_readline()

     def load_frame(self, frame_size):
         if self.current_frame and self.current_frame.read() != b'':
             raise UnpicklingError(
                 "beginning of a new frame before end of current frame")
         self.current_frame = io.BytesIO(self.file_read(frame_size))

 # Tools used for pickling.

 def _getattribute(obj, name):
     for subpath in name.split('.'):
         if subpath == '<locals>':
             raise AttributeError("Can't get local attribute {!r} on {!r}"
                                  .format(name, obj))
         try:
             parent = obj
             obj = getattr(obj, subpath)
         except AttributeError:
             raise AttributeError("Can't get attribute {!r} on {!r}"
                                  .format(name, obj))
     return obj, parent

 def whichmodule(obj, name):
     """Find the module an object belong to."""
     module_name = getattr(obj, '__module__', None)
     if module_name is not None:
         return module_name
     # Protect the iteration by using a list copy of sys.modules against dynamic
     # modules that trigger imports of other modules upon calls to getattr.
     for module_name, module in list(sys.modules.items()):
         if module_name == '__main__' or module is None:
             continue
         try:
             if _getattribute(module, name)[0] is obj:
                 return module_name
         except AttributeError:
             pass
     return '__main__'

 def encode_long(x):
     r"""Encode a long to a two's complement little-endian binary string.
     Note that 0 is a special case, returning an empty string, to save a
     byte in the LONG1 pickling context.

     >>> encode_long(0)
     b''
     >>> encode_long(255)
     b'\xff\x00'
     >>> encode_long(32767)
     b'\xff\x7f'
     >>> encode_long(-256)
     b'\x00\xff'
     >>> encode_long(-32768)
     b'\x00\x80'
     >>> encode_long(-128)
     b'\x80'
     >>> encode_long(127)
     b'\x7f'
     >>>
     """
     if x == 0:
         return b''
     nbytes = (x.bit_length() >> 3) + 1
     result = x.to_bytes(nbytes, byteorder='little', signed=True)
     if x < 0 and nbytes > 1:
         if result[-1] == 0xff and (result[-2] & 0x80) != 0:
             result = result[:-1]
     return result

 def decode_long(data):
     r"""Decode a long from a two's complement little-endian binary string.

     >>> decode_long(b'')
     0
     >>> decode_long(b"\xff\x00")
     255
     >>> decode_long(b"\xff\x7f")
     32767
     >>> decode_long(b"\x00\xff")
     -256
     >>> decode_long(b"\x00\x80")
     -32768
     >>> decode_long(b"\x80")
     -128
     >>> decode_long(b"\x7f")
     127
     """
     return int.from_bytes(data, byteorder='little', signed=True)

 # Pickling machinery

 class _Pickler:

     def __init__(self, file, protocol=None, *, fix_imports=True):
         """This takes a binary file for writing a pickle data stream.

         The optional *protocol* argument tells the pickler to use the
         given protocol; supported protocols are 0, 1, 2, 3 and 4.  The
         default protocol is 3; a backward-incompatible protocol designed
         for Python 3.

         Specifying a negative protocol version selects the highest
         protocol version supported.  The higher the protocol used, the
         more recent the version of Python needed to read the pickle
         produced.

         The *file* argument must have a write() method that accepts a
         single bytes argument. It can thus be a file object opened for
         binary writing, an io.BytesIO instance, or any other custom
         object that meets this interface.

         If *fix_imports* is True and *protocol* is less than 3, pickle
         will try to map the new Python 3 names to the old module names
         used in Python 2, so that the pickle data stream is readable
         with Python 2.
         """
         if protocol is None:
             protocol = DEFAULT_PROTOCOL
         if protocol < 0:
             protocol = HIGHEST_PROTOCOL
         elif not 0 <= protocol <= HIGHEST_PROTOCOL:
             raise ValueError("pickle protocol must be <= %d" % HIGHEST_PROTOCOL)
         try:
             self._file_write = file.write
         except AttributeError:
             raise TypeError("file must have a 'write' attribute")
         self.framer = _Framer(self._file_write)
         self.write = self.framer.write
         self.memo = {}
         self.proto = int(protocol)
         self.bin = protocol >= 1
         self.fast = 0
         self.fix_imports = fix_imports and protocol < 3

     def clear_memo(self):
         """Clears the pickler's "memo".

         The memo is the data structure that remembers which objects the
         pickler has already seen, so that shared or recursive objects
         are pickled by reference and not by value.  This method is
         useful when re-using picklers.
         """
         self.memo.clear()

     def dump(self, obj):
         """Write a pickled representation of obj to the open file."""
         # Check whether Pickler was initialized correctly. This is
         # only needed to mimic the behavior of _pickle.Pickler.dump().
         if not hasattr(self, "_file_write"):
             raise PicklingError("Pickler.__init__() was not called by "
                                 "%s.__init__()" % (self.__class__.__name__,))
         if self.proto >= 2:
             self.write(PROTO + pack("<B", self.proto))
         if self.proto >= 4:
             self.framer.start_framing()
         self.save(obj)
         self.write(STOP)
         self.framer.end_framing()

     def memoize(self, obj):
         """Store an object in the memo."""

         # The Pickler memo is a dictionary mapping object ids to 2-tuples
         # that contain the Unpickler memo key and the object being memoized.
         # The memo key is written to the pickle and will become
         # the key in the Unpickler's memo.  The object is stored in the
         # Pickler memo so that transient objects are kept alive during
         # pickling.

         # The use of the Unpickler memo length as the memo key is just a
         # convention.  The only requirement is that the memo values be unique.
         # But there appears no advantage to any other scheme, and this
         # scheme allows the Unpickler memo to be implemented as a plain (but
         # growable) array, indexed by memo key.
         if self.fast:
             return
         assert id(obj) not in self.memo
         idx = len(self.memo)
         self.write(self.put(idx))
         self.memo[id(obj)] = idx, obj

     # Return a PUT (BINPUT, LONG_BINPUT) opcode string, with argument i.
     def put(self, idx):
         if self.proto >= 4:
             return MEMOIZE
         elif self.bin:
             if idx < 256:
                 return BINPUT + pack("<B", idx)
             else:
                 return LONG_BINPUT + pack("<I", idx)
         else:
             return PUT + repr(idx).encode("ascii") + b'\n'

     # Return a GET (BINGET, LONG_BINGET) opcode string, with argument i.
     def get(self, i):
         if self.bin:
             if i < 256:
                 return BINGET + pack("<B", i)
             else:
                 return LONG_BINGET + pack("<I", i)

         return GET + repr(i).encode("ascii") + b'\n'

     def save(self, obj, save_persistent_id=True):
         self.framer.commit_frame()

         # Check for persistent id (defined by a subclass)
         pid = self.persistent_id(obj)
         if pid is not None and save_persistent_id:
             self.save_pers(pid)
             return

         # Check the memo
         x = self.memo.get(id(obj))
         if x is not None:
             self.write(self.get(x[0]))
             return

         # Check the type dispatch table
         t = type(obj)
         f = self.dispatch.get(t)
         if f is not None:
             f(self, obj) # Call unbound method with explicit self
             return

         # Check private dispatch table if any, or else copyreg.dispatch_table
         reduce = getattr(self, 'dispatch_table', dispatch_table).get(t)
         if reduce is not None:
             rv = reduce(obj)
         else:
             # Check for a class with a custom metaclass; treat as regular class
             try:
                 issc = issubclass(t, type)
             except TypeError: # t is not a class (old Boost; see SF #502085)
                 issc = False
             if issc:
                 self.save_global(obj)
                 return

             # Check for a __reduce_ex__ method, fall back to __reduce__
             reduce = getattr(obj, "__reduce_ex__", None)
             if reduce is not None:
                 rv = reduce(self.proto)
             else:
                 reduce = getattr(obj, "__reduce__", None)
                 if reduce is not None:
                     rv = reduce()
                 else:
                     raise PicklingError("Can't pickle %r object: %r" %
                                         (t.__name__, obj))

         # Check for string returned by reduce(), meaning "save as global"
         if isinstance(rv, str):
             self.save_global(obj, rv)
             return

         # Assert that reduce() returned a tuple
         if not isinstance(rv, tuple):
             raise PicklingError("%s must return string or tuple" % reduce)

         # Assert that it returned an appropriately sized tuple
         l = len(rv)
         if not (2 <= l <= 5):
             raise PicklingError("Tuple returned by %s must have "
                                 "two to five elements" % reduce)

         # Save the reduce() output and finally memoize the object
         self.save_reduce(obj=obj, *rv)

     def persistent_id(self, obj):
         # This exists so a subclass can override it
         return None

     def save_pers(self, pid):
         # Save a persistent id reference
         if self.bin:
             self.save(pid, save_persistent_id=False)
             self.write(BINPERSID)
         else:
             try:
                 self.write(PERSID + str(pid).encode("ascii") + b'\n')
             except UnicodeEncodeError:
                 raise PicklingError(
                     "persistent IDs in protocol 0 must be ASCII strings")

     def save_reduce(self, func, args, state=None, listitems=None,
                     dictitems=None, obj=None):
         # This API is called by some subclasses

         if not isinstance(args, tuple):
             raise PicklingError("args from save_reduce() must be a tuple")
         if not callable(func):
             raise PicklingError("func from save_reduce() must be callable")

         save = self.save
         write = self.write

         func_name = getattr(func, "__name__", "")
         if self.proto >= 2 and func_name == "__newobj_ex__":
             cls, args, kwargs = args
             if not hasattr(cls, "__new__"):
                 raise PicklingError("args[0] from {} args has no __new__"
                                     .format(func_name))
             if obj is not None and cls is not obj.__class__:
                 raise PicklingError("args[0] from {} args has the wrong class"
                                     .format(func_name))
             if self.proto >= 4:
                 save(cls)
                 save(args)
                 save(kwargs)
                 write(NEWOBJ_EX)
             else:
                 func = partial(cls.__new__, cls, *args, **kwargs)
                 save(func)
                 save(())
                 write(REDUCE)
         elif self.proto >= 2 and func_name == "__newobj__":
             # A __reduce__ implementation can direct protocol 2 or newer to
             # use the more efficient NEWOBJ opcode, while still
             # allowing protocol 0 and 1 to work normally.  For this to
             # work, the function returned by __reduce__ should be
             # called __newobj__, and its first argument should be a
             # class.  The implementation for __newobj__
             # should be as follows, although pickle has no way to
             # verify this:
             #
             # def __newobj__(cls, *args):
             #     return cls.__new__(cls, *args)
             #
             # Protocols 0 and 1 will pickle a reference to __newobj__,
             # while protocol 2 (and above) will pickle a reference to
             # cls, the remaining args tuple, and the NEWOBJ code,
             # which calls cls.__new__(cls, *args) at unpickling time
             # (see load_newobj below).  If __reduce__ returns a
             # three-tuple, the state from the third tuple item will be
             # pickled regardless of the protocol, calling __setstate__
             # at unpickling time (see load_build below).
             #
             # Note that no standard __newobj__ implementation exists;
             # you have to provide your own.  This is to enforce
             # compatibility with Python 2.2 (pickles written using
             # protocol 0 or 1 in Python 2.3 should be unpicklable by
             # Python 2.2).
             cls = args[0]
             if not hasattr(cls, "__new__"):
                 raise PicklingError(
                     "args[0] from __newobj__ args has no __new__")
             if obj is not None and cls is not obj.__class__:
                 raise PicklingError(
                     "args[0] from __newobj__ args has the wrong class")
             args = args[1:]
             save(cls)
             save(args)
             write(NEWOBJ)
         else:
             save(func)
             save(args)
             write(REDUCE)

         if obj is not None:
             # If the object is already in the memo, this means it is
             # recursive. In this case, throw away everything we put on the
             # stack, and fetch the object back from the memo.
             if id(obj) in self.memo:
                 write(POP + self.get(self.memo[id(obj)][0]))
             else:
                 self.memoize(obj)

         # More new special cases (that work with older protocols as
         # well): when __reduce__ returns a tuple with 4 or 5 items,
         # the 4th and 5th item should be iterators that provide list
         # items and dict items (as (key, value) tuples), or None.

         if listitems is not None:
             self._batch_appends(listitems)

         if dictitems is not None:
             self._batch_setitems(dictitems)

         if state is not None:
             save(state)
             write(BUILD)

     # Methods below this point are dispatched through the dispatch table

     dispatch = {}

     def save_none(self, obj):
         self.write(NONE)
     dispatch[type(None)] = save_none

     def save_bool(self, obj):
         if self.proto >= 2:
             self.write(NEWTRUE if obj else NEWFALSE)
         else:
             self.write(TRUE if obj else FALSE)
     dispatch[bool] = save_bool

     def save_long(self, obj):
         if self.bin:
             # If the int is small enough to fit in a signed 4-byte 2's-comp
             # format, we can store it more efficiently than the general
             # case.
             # First one- and two-byte unsigned ints:
             if obj >= 0:
                 if obj <= 0xff:
                     self.write(BININT1 + pack("<B", obj))
                     return
                 if obj <= 0xffff:
                     self.write(BININT2 + pack("<H", obj))
                     return
             # Next check for 4-byte signed ints:
             if -0x80000000 <= obj <= 0x7fffffff:
                 self.write(BININT + pack("<i", obj))
                 return
         if self.proto >= 2:
             encoded = encode_long(obj)
             n = len(encoded)
             if n < 256:
                 self.write(LONG1 + pack("<B", n) + encoded)
             else:
                 self.write(LONG4 + pack("<i", n) + encoded)
             return
         self.write(LONG + repr(obj).encode("ascii") + b'L\n')
     dispatch[int] = save_long

     def save_float(self, obj):
         if self.bin:
             self.write(BINFLOAT + pack('>d', obj))
         else:
             self.write(FLOAT + repr(obj).encode("ascii") + b'\n')
     dispatch[float] = save_float

     def save_bytes(self, obj):
         if self.proto < 3:
             if not obj: # bytes object is empty
                 self.save_reduce(bytes, (), obj=obj)
             else:
                 self.save_reduce(codecs.encode,
                                  (str(obj, 'latin1'), 'latin1'), obj=obj)
             return
         n = len(obj)
         if n <= 0xff:
             self.write(SHORT_BINBYTES + pack("<B", n) + obj)
         elif n > 0xffffffff and self.proto >= 4:
             self.write(BINBYTES8 + pack("<Q", n) + obj)
         else:
             self.write(BINBYTES + pack("<I", n) + obj)
         self.memoize(obj)
     dispatch[bytes] = save_bytes

     def save_str(self, obj):
         if self.bin:
             encoded = obj.encode('utf-8', 'surrogatepass')
             n = len(encoded)
             if n <= 0xff and self.proto >= 4:
                 self.write(SHORT_BINUNICODE + pack("<B", n) + encoded)
             elif n > 0xffffffff and self.proto >= 4:
                 self.write(BINUNICODE8 + pack("<Q", n) + encoded)
             else:
                 self.write(BINUNICODE + pack("<I", n) + encoded)
         else:
             obj = obj.replace("\\", "\\u005c")
             obj = obj.replace("\n", "\\u000a")
             self.write(UNICODE + obj.encode('raw-unicode-escape') +
                        b'\n')
         self.memoize(obj)
     dispatch[str] = save_str

     def save_tuple(self, obj):
         if not obj: # tuple is empty
             if self.bin:
                 self.write(EMPTY_TUPLE)
             else:
                 self.write(MARK + TUPLE)
             return

         n = len(obj)
         save = self.save
         memo = self.memo
         if n <= 3 and self.proto >= 2:
             for element in obj:
                 save(element)
             # Subtle.  Same as in the big comment below.
             if id(obj) in memo:
                 get = self.get(memo[id(obj)][0])
                 self.write(POP * n + get)
             else:
                 self.write(_tuplesize2code[n])
                 self.memoize(obj)
             return

         # proto 0 or proto 1 and tuple isn't empty, or proto > 1 and tuple
         # has more than 3 elements.
         write = self.write
         write(MARK)
         for element in obj:
             save(element)

         if id(obj) in memo:
             # Subtle.  d was not in memo when we entered save_tuple(), so
             # the process of saving the tuple's elements must have saved
             # the tuple itself:  the tuple is recursive.  The proper action
             # now is to throw away everything we put on the stack, and
             # simply GET the tuple (it's already constructed).  This check
             # could have been done in the "for element" loop instead, but
             # recursive tuples are a rare thing.
             get = self.get(memo[id(obj)][0])
             if self.bin:
                 write(POP_MARK + get)
             else:   # proto 0 -- POP_MARK not available
                 write(POP * (n+1) + get)
             return

         # No recursion.
         write(TUPLE)
         self.memoize(obj)

     dispatch[tuple] = save_tuple

     def save_list(self, obj):
         if self.bin:
             self.write(EMPTY_LIST)
         else:   # proto 0 -- can't use EMPTY_LIST
             self.write(MARK + LIST)

         self.memoize(obj)
         self._batch_appends(obj)

     dispatch[list] = save_list

     _BATCHSIZE = 1000

     def _batch_appends(self, items):
         # Helper to batch up APPENDS sequences
         save = self.save
         write = self.write

         if not self.bin:
             for x in items:
                 save(x)
                 write(APPEND)
             return

         it = iter(items)
         while True:
             tmp = list(islice(it, self._BATCHSIZE))
             n = len(tmp)
             if n > 1:
                 write(MARK)
                 for x in tmp:
                     save(x)
                 write(APPENDS)
             elif n:
                 save(tmp[0])
                 write(APPEND)
             # else tmp is empty, and we're done
             if n < self._BATCHSIZE:
                 return

     def save_dict(self, obj):
         if self.bin:
             self.write(EMPTY_DICT)
         else:   # proto 0 -- can't use EMPTY_DICT
             self.write(MARK + DICT)

         self.memoize(obj)
         self._batch_setitems(obj.items())

     dispatch[dict] = save_dict
     if PyStringMap is not None:
         dispatch[PyStringMap] = save_dict

     def _batch_setitems(self, items):
         # Helper to batch up SETITEMS sequences; proto >= 1 only
         save = self.save
         write = self.write

         if not self.bin:
             for k, v in items:
                 save(k)
                 save(v)
                 write(SETITEM)
             return

         it = iter(items)
         while True:
             tmp = list(islice(it, self._BATCHSIZE))
             n = len(tmp)
             if n > 1:
                 write(MARK)
                 for k, v in tmp:
                     save(k)
                     save(v)
                 write(SETITEMS)
             elif n:
                 k, v = tmp[0]
                 save(k)
                 save(v)
                 write(SETITEM)
             # else tmp is empty, and we're done
             if n < self._BATCHSIZE:
                 return

     def save_set(self, obj):
         save = self.save
         write = self.write

         if self.proto < 4:
             self.save_reduce(set, (list(obj),), obj=obj)
             return

         write(EMPTY_SET)
         self.memoize(obj)

         it = iter(obj)
         while True:
             batch = list(islice(it, self._BATCHSIZE))
             n = len(batch)
             if n > 0:
                 write(MARK)
                 for item in batch:
                     save(item)
                 write(ADDITEMS)
             if n < self._BATCHSIZE:
                 return
     dispatch[set] = save_set

     def save_frozenset(self, obj):
         save = self.save
         write = self.write

         if self.proto < 4:
             self.save_reduce(frozenset, (list(obj),), obj=obj)
             return

         write(MARK)
         for item in obj:
             save(item)

         if id(obj) in self.memo:
             # If the object is already in the memo, this means it is
             # recursive. In this case, throw away everything we put on the
             # stack, and fetch the object back from the memo.
             write(POP_MARK + self.get(self.memo[id(obj)][0]))
             return

         write(FROZENSET)
         self.memoize(obj)
     dispatch[frozenset] = save_frozenset

     def save_global(self, obj, name=None):
         write = self.write
         memo = self.memo

         if name is None:
             name = getattr(obj, '__qualname__', None)
         if name is None:
             name = obj.__name__

         module_name = whichmodule(obj, name)
         try:
             __import__(module_name, level=0)
             module = sys.modules[module_name]
             obj2, parent = _getattribute(module, name)
         except (ImportError, KeyError, AttributeError):
             raise PicklingError(
                 "Can't pickle %r: it's not found as %s.%s" %
                 (obj, module_name, name))
         else:
             if obj2 is not obj:
                 raise PicklingError(
                     "Can't pickle %r: it's not the same object as %s.%s" %
                     (obj, module_name, name))

         if self.proto >= 2:
             code = _extension_registry.get((module_name, name))
             if code:
                 assert code > 0
                 if code <= 0xff:
                     write(EXT1 + pack("<B", code))
                 elif code <= 0xffff:
                     write(EXT2 + pack("<H", code))
                 else:
                     write(EXT4 + pack("<i", code))
                 return
         lastname = name.rpartition('.')[2]
         if parent is module:
             name = lastname
         # Non-ASCII identifiers are supported only with protocols >= 3.
         if self.proto >= 4:
             self.save(module_name)
             self.save(name)
             write(STACK_GLOBAL)
         elif parent is not module:
             self.save_reduce(getattr, (parent, lastname))
         elif self.proto >= 3:
             write(GLOBAL + bytes(module_name, "utf-8") + b'\n' +
                   bytes(name, "utf-8") + b'\n')
         else:
             if self.fix_imports:
                 r_name_mapping = _compat_pickle.REVERSE_NAME_MAPPING
                 r_import_mapping = _compat_pickle.REVERSE_IMPORT_MAPPING
                 if (module_name, name) in r_name_mapping:
                     module_name, name = r_name_mapping[(module_name, name)]
                 elif module_name in r_import_mapping:
                     module_name = r_import_mapping[module_name]
             try:
                 write(GLOBAL + bytes(module_name, "ascii") + b'\n' +
                       bytes(name, "ascii") + b'\n')
             except UnicodeEncodeError:
                 raise PicklingError(
                     "can't pickle global identifier '%s.%s' using "
                     "pickle protocol %i" % (module, name, self.proto))

         self.memoize(obj)

     def save_type(self, obj):
         if obj is type(None):
             return self.save_reduce(type, (None,), obj=obj)
         elif obj is type(NotImplemented):
             return self.save_reduce(type, (NotImplemented,), obj=obj)
         elif obj is type(...):
             return self.save_reduce(type, (...,), obj=obj)
         return self.save_global(obj)

     dispatch[FunctionType] = save_global
     dispatch[type] = save_type

 # Unpickling machinery

 class _Unpickler:

     def __init__(self, file, *, fix_imports=True,
                  encoding="ASCII", errors="strict"):
         """This takes a binary file for reading a pickle data stream.

         The protocol version of the pickle is detected automatically, so
         no proto argument is needed.

         The argument *file* must have two methods, a read() method that
         takes an integer argument, and a readline() method that requires
         no arguments.  Both methods should return bytes.  Thus *file*
         can be a binary file object opened for reading, an io.BytesIO
         object, or any other custom object that meets this interface.

         The file-like object must have two methods, a read() method
         that takes an integer argument, and a readline() method that
         requires no arguments.  Both methods should return bytes.
         Thus file-like object can be a binary file object opened for
         reading, a BytesIO object, or any other custom object that
         meets this interface.

         Optional keyword arguments are *fix_imports*, *encoding* and
         *errors*, which are used to control compatibility support for
         pickle stream generated by Python 2.  If *fix_imports* is True,
         pickle will try to map the old Python 2 names to the new names
         used in Python 3.  The *encoding* and *errors* tell pickle how
         to decode 8-bit string instances pickled by Python 2; these
         default to 'ASCII' and 'strict', respectively. *encoding* can be
         'bytes' to read theses 8-bit string instances as bytes objects.
         """
         self._file_readline = file.readline
         self._file_read = file.read
         self.memo = {}
         self.encoding = encoding
         self.errors = errors
         self.proto = 0
         self.fix_imports = fix_imports

     def load(self):
         """Read a pickled object representation from the open file.

         Return the reconstituted object hierarchy specified in the file.
         """
         # Check whether Unpickler was initialized correctly. This is
         # only needed to mimic the behavior of _pickle.Unpickler.dump().
         if not hasattr(self, "_file_read"):
             raise UnpicklingError("Unpickler.__init__() was not called by "
                                   "%s.__init__()" % (self.__class__.__name__,))
         self._unframer = _Unframer(self._file_read, self._file_readline)
         self.read = self._unframer.read
         self.readline = self._unframer.readline
         self.metastack = []
         self.stack = []
         self.append = self.stack.append
         self.proto = 0
         read = self.read
         dispatch = self.dispatch
         try:
             while True:
                 key = read(1)
                 if not key:
                     raise EOFError
                 assert isinstance(key, bytes_types)
                 dispatch[key[0]](self)
         except _Stop as stopinst:
             return stopinst.value

     # Return a list of items pushed in the stack after last MARK instruction.
     def pop_mark(self):
         items = self.stack
         self.stack = self.metastack.pop()
         self.append = self.stack.append
         return items

     def persistent_load(self, pid):
         raise UnpicklingError("unsupported persistent id encountered")

     dispatch = {}

     def load_proto(self):
         proto = self.read(1)[0]
         if not 0 <= proto <= HIGHEST_PROTOCOL:
             raise ValueError("unsupported pickle protocol: %d" % proto)
         self.proto = proto
     dispatch[PROTO[0]] = load_proto

     def load_frame(self):
         frame_size, = unpack('<Q', self.read(8))
         if frame_size > sys.maxsize:
             raise ValueError("frame size > sys.maxsize: %d" % frame_size)
         self._unframer.load_frame(frame_size)
     dispatch[FRAME[0]] = load_frame

     def load_persid(self):
         try:
             pid = self.readline()[:-1].decode("ascii")
         except UnicodeDecodeError:
             raise UnpicklingError(
                 "persistent IDs in protocol 0 must be ASCII strings")
         self.append(self.persistent_load(pid))
     dispatch[PERSID[0]] = load_persid

     def load_binpersid(self):
         pid = self.stack.pop()
         self.append(self.persistent_load(pid))
     dispatch[BINPERSID[0]] = load_binpersid

     def load_none(self):
         self.append(None)
     dispatch[NONE[0]] = load_none

     def load_false(self):
         self.append(False)
     dispatch[NEWFALSE[0]] = load_false

     def load_true(self):
         self.append(True)
     dispatch[NEWTRUE[0]] = load_true

     def load_int(self):
         data = self.readline()
         if data == FALSE[1:]:
             val = False
         elif data == TRUE[1:]:
             val = True
         else:
             val = int(data, 0)
         self.append(val)
     dispatch[INT[0]] = load_int

     def load_binint(self):
         self.append(unpack('<i', self.read(4))[0])
     dispatch[BININT[0]] = load_binint

     def load_binint1(self):
         self.append(self.read(1)[0])
     dispatch[BININT1[0]] = load_binint1

     def load_binint2(self):
         self.append(unpack('<H', self.read(2))[0])
     dispatch[BININT2[0]] = load_binint2

     def load_long(self):
         val = self.readline()[:-1]
         if val and val[-1] == b'L'[0]:
             val = val[:-1]
         self.append(int(val, 0))
     dispatch[LONG[0]] = load_long

     def load_long1(self):
         n = self.read(1)[0]
         data = self.read(n)
         self.append(decode_long(data))
     dispatch[LONG1[0]] = load_long1

     def load_long4(self):
         n, = unpack('<i', self.read(4))
         if n < 0:
             # Corrupt or hostile pickle -- we never write one like this
             raise UnpicklingError("LONG pickle has negative byte count")
         data = self.read(n)
         self.append(decode_long(data))
     dispatch[LONG4[0]] = load_long4

     def load_float(self):
         self.append(float(self.readline()[:-1]))
     dispatch[FLOAT[0]] = load_float

     def load_binfloat(self):
         self.append(unpack('>d', self.read(8))[0])
     dispatch[BINFLOAT[0]] = load_binfloat

     def _decode_string(self, value):
         # Used to allow strings from Python 2 to be decoded either as
         # bytes or Unicode strings.  This should be used only with the
         # STRING, BINSTRING and SHORT_BINSTRING opcodes.
         if self.encoding == "bytes":
             return value
         else:
             return value.decode(self.encoding, self.errors)

     def load_string(self):
         data = self.readline()[:-1]
         # Strip outermost quotes
         if len(data) >= 2 and data[0] == data[-1] and data[0] in b'"\'':
             data = data[1:-1]
         else:
             raise UnpicklingError("the STRING opcode argument must be quoted")
         self.append(self._decode_string(codecs.escape_decode(data)[0]))
     dispatch[STRING[0]] = load_string

     def load_binstring(self):
         # Deprecated BINSTRING uses signed 32-bit length
         len, = unpack('<i', self.read(4))
         if len < 0:
             raise UnpicklingError("BINSTRING pickle has negative byte count")
         data = self.read(len)
         self.append(self._decode_string(data))
     dispatch[BINSTRING[0]] = load_binstring

     def load_binbytes(self):
         len, = unpack('<I', self.read(4))
         if len > maxsize:
             raise UnpicklingError("BINBYTES exceeds system's maximum size "
                                   "of %d bytes" % maxsize)
         self.append(self.read(len))
     dispatch[BINBYTES[0]] = load_binbytes

     def load_unicode(self):
         self.append(str(self.readline()[:-1], 'raw-unicode-escape'))
     dispatch[UNICODE[0]] = load_unicode

     def load_binunicode(self):
         len, = unpack('<I', self.read(4))
         if len > maxsize:
             raise UnpicklingError("BINUNICODE exceeds system's maximum size "
                                   "of %d bytes" % maxsize)
         self.append(str(self.read(len), 'utf-8', 'surrogatepass'))
     dispatch[BINUNICODE[0]] = load_binunicode

     def load_binunicode8(self):
         len, = unpack('<Q', self.read(8))
         if len > maxsize:
             raise UnpicklingError("BINUNICODE8 exceeds system's maximum size "
                                   "of %d bytes" % maxsize)
         self.append(str(self.read(len), 'utf-8', 'surrogatepass'))
     dispatch[BINUNICODE8[0]] = load_binunicode8

     def load_binbytes8(self):
         len, = unpack('<Q', self.read(8))
         if len > maxsize:
             raise UnpicklingError("BINBYTES8 exceeds system's maximum size "
                                   "of %d bytes" % maxsize)
         self.append(self.read(len))
     dispatch[BINBYTES8[0]] = load_binbytes8

     def load_short_binstring(self):
         len = self.read(1)[0]
         data = self.read(len)
         self.append(self._decode_string(data))
     dispatch[SHORT_BINSTRING[0]] = load_short_binstring

     def load_short_binbytes(self):
         len = self.read(1)[0]
         self.append(self.read(len))
     dispatch[SHORT_BINBYTES[0]] = load_short_binbytes

     def load_short_binunicode(self):
         len = self.read(1)[0]
         self.append(str(self.read(len), 'utf-8', 'surrogatepass'))
     dispatch[SHORT_BINUNICODE[0]] = load_short_binunicode

     def load_tuple(self):
         items = self.pop_mark()
         self.append(tuple(items))
     dispatch[TUPLE[0]] = load_tuple

     def load_empty_tuple(self):
         self.append(())
     dispatch[EMPTY_TUPLE[0]] = load_empty_tuple

     def load_tuple1(self):
         self.stack[-1] = (self.stack[-1],)
     dispatch[TUPLE1[0]] = load_tuple1

     def load_tuple2(self):
         self.stack[-2:] = [(self.stack[-2], self.stack[-1])]
     dispatch[TUPLE2[0]] = load_tuple2

     def load_tuple3(self):
         self.stack[-3:] = [(self.stack[-3], self.stack[-2], self.stack[-1])]
     dispatch[TUPLE3[0]] = load_tuple3

     def load_empty_list(self):
         self.append([])
     dispatch[EMPTY_LIST[0]] = load_empty_list

     def load_empty_dictionary(self):
         self.append({})
     dispatch[EMPTY_DICT[0]] = load_empty_dictionary

     def load_empty_set(self):
         self.append(set())
     dispatch[EMPTY_SET[0]] = load_empty_set

     def load_frozenset(self):
         items = self.pop_mark()
         self.append(frozenset(items))
     dispatch[FROZENSET[0]] = load_frozenset

     def load_list(self):
         items = self.pop_mark()
         self.append(items)
     dispatch[LIST[0]] = load_list

     def load_dict(self):
         items = self.pop_mark()
         d = {items[i]: items[i+1]
              for i in range(0, len(items), 2)}
         self.append(d)
     dispatch[DICT[0]] = load_dict

     # INST and OBJ differ only in how they get a class object.  It's not
     # only sensible to do the rest in a common routine, the two routines
     # previously diverged and grew different bugs.
     # klass is the class to instantiate, and k points to the topmost mark
     # object, following which are the arguments for klass.__init__.
     def _instantiate(self, klass, args):
         if (args or not isinstance(klass, type) or
             hasattr(klass, "__getinitargs__")):
             try:
                 value = klass(*args)
             except TypeError as err:
                 raise TypeError("in constructor for %s: %s" %
                                 (klass.__name__, str(err)), sys.exc_info()[2])
         else:
             value = klass.__new__(klass)
         self.append(value)

     def load_inst(self):
         module = self.readline()[:-1].decode("ascii")
         name = self.readline()[:-1].decode("ascii")
         klass = self.find_class(module, name)
         self._instantiate(klass, self.pop_mark())
     dispatch[INST[0]] = load_inst

     def load_obj(self):
         # Stack is ... markobject classobject arg1 arg2 ...
         args = self.pop_mark()
         cls = args.pop(0)
         self._instantiate(cls, args)
     dispatch[OBJ[0]] = load_obj

     def load_newobj(self):
         args = self.stack.pop()
         cls = self.stack.pop()
         obj = cls.__new__(cls, *args)
         self.append(obj)
     dispatch[NEWOBJ[0]] = load_newobj

     def load_newobj_ex(self):
         kwargs = self.stack.pop()
         args = self.stack.pop()
         cls = self.stack.pop()
         obj = cls.__new__(cls, *args, **kwargs)
         self.append(obj)
     dispatch[NEWOBJ_EX[0]] = load_newobj_ex

     def load_global(self):
         module = self.readline()[:-1].decode("utf-8")
         name = self.readline()[:-1].decode("utf-8")
         klass = self.find_class(module, name)
         self.append(klass)
     dispatch[GLOBAL[0]] = load_global

     def load_stack_global(self):
         name = self.stack.pop()
         module = self.stack.pop()
         if type(name) is not str or type(module) is not str:
             raise UnpicklingError("STACK_GLOBAL requires str")
         self.append(self.find_class(module, name))
     dispatch[STACK_GLOBAL[0]] = load_stack_global

     def load_ext1(self):
         code = self.read(1)[0]
         self.get_extension(code)
     dispatch[EXT1[0]] = load_ext1

     def load_ext2(self):
         code, = unpack('<H', self.read(2))
         self.get_extension(code)
     dispatch[EXT2[0]] = load_ext2

     def load_ext4(self):
         code, = unpack('<i', self.read(4))
         self.get_extension(code)
     dispatch[EXT4[0]] = load_ext4

     def get_extension(self, code):
         nil = []
         obj = _extension_cache.get(code, nil)
         if obj is not nil:
             self.append(obj)
             return
         key = _inverted_registry.get(code)
         if not key:
             if code <= 0: # note that 0 is forbidden
                 # Corrupt or hostile pickle.
                 raise UnpicklingError("EXT specifies code <= 0")
             raise ValueError("unregistered extension code %d" % code)
         obj = self.find_class(*key)
         _extension_cache[code] = obj
         self.append(obj)

     def find_class(self, module, name):
         # Subclasses may override this.
         if self.proto < 3 and self.fix_imports:
             if (module, name) in _compat_pickle.NAME_MAPPING:
                 module, name = _compat_pickle.NAME_MAPPING[(module, name)]
             elif module in _compat_pickle.IMPORT_MAPPING:
                 module = _compat_pickle.IMPORT_MAPPING[module]
         __import__(module, level=0)
         if self.proto >= 4:
             return _getattribute(sys.modules[module], name)[0]
         else:
             return getattr(sys.modules[module], name)

     def load_reduce(self):
         stack = self.stack
         args = stack.pop()
         func = stack[-1]
         stack[-1] = func(*args)
     dispatch[REDUCE[0]] = load_reduce

     def load_pop(self):
         if self.stack:
             del self.stack[-1]
         else:
             self.pop_mark()
     dispatch[POP[0]] = load_pop

     def load_pop_mark(self):
         self.pop_mark()
     dispatch[POP_MARK[0]] = load_pop_mark

     def load_dup(self):
         self.append(self.stack[-1])
     dispatch[DUP[0]] = load_dup

     def load_get(self):
         i = int(self.readline()[:-1])
         self.append(self.memo[i])
     dispatch[GET[0]] = load_get

     def load_binget(self):
         i = self.read(1)[0]
         self.append(self.memo[i])
     dispatch[BINGET[0]] = load_binget

     def load_long_binget(self):
         i, = unpack('<I', self.read(4))
         self.append(self.memo[i])
     dispatch[LONG_BINGET[0]] = load_long_binget

     def load_put(self):
         i = int(self.readline()[:-1])
         if i < 0:
             raise ValueError("negative PUT argument")
         self.memo[i] = self.stack[-1]
     dispatch[PUT[0]] = load_put

     def load_binput(self):
         i = self.read(1)[0]
         if i < 0:
             raise ValueError("negative BINPUT argument")
         self.memo[i] = self.stack[-1]
     dispatch[BINPUT[0]] = load_binput

     def load_long_binput(self):
         i, = unpack('<I', self.read(4))
         if i > maxsize:
             raise ValueError("negative LONG_BINPUT argument")
         self.memo[i] = self.stack[-1]
     dispatch[LONG_BINPUT[0]] = load_long_binput

     def load_memoize(self):
         memo = self.memo
         memo[len(memo)] = self.stack[-1]
     dispatch[MEMOIZE[0]] = load_memoize

     def load_append(self):
         stack = self.stack
         value = stack.pop()
         list = stack[-1]
         list.append(value)
     dispatch[APPEND[0]] = load_append

     def load_appends(self):
         items = self.pop_mark()
         list_obj = self.stack[-1]
         if isinstance(list_obj, list):
             list_obj.extend(items)
         else:
             append = list_obj.append
             for item in items:
                 append(item)
     dispatch[APPENDS[0]] = load_appends

     def load_setitem(self):
         stack = self.stack
         value = stack.pop()
         key = stack.pop()
         dict = stack[-1]
         dict[key] = value
     dispatch[SETITEM[0]] = load_setitem

     def load_setitems(self):
         items = self.pop_mark()
         dict = self.stack[-1]
         for i in range(0, len(items), 2):
             dict[items[i]] = items[i + 1]
     dispatch[SETITEMS[0]] = load_setitems

     def load_additems(self):
         items = self.pop_mark()
         set_obj = self.stack[-1]
         if isinstance(set_obj, set):
             set_obj.update(items)
         else:
             add = set_obj.add
             for item in items:
                 add(item)
     dispatch[ADDITEMS[0]] = load_additems

     def load_build(self):
         stack = self.stack
         state = stack.pop()
         inst = stack[-1]
         setstate = getattr(inst, "__setstate__", None)
         if setstate is not None:
             setstate(state)
             return
         slotstate = None
         if isinstance(state, tuple) and len(state) == 2:
             state, slotstate = state
         if state:
             inst_dict = inst.__dict__
             intern = sys.intern
             for k, v in state.items():
                 if type(k) is str:
                     inst_dict[intern(k)] = v
                 else:
                     inst_dict[k] = v
         if slotstate:
             for k, v in slotstate.items():
                 setattr(inst, k, v)
     dispatch[BUILD[0]] = load_build

     def load_mark(self):
         self.metastack.append(self.stack)
         self.stack = []
         self.append = self.stack.append
     dispatch[MARK[0]] = load_mark

     def load_stop(self):
         value = self.stack.pop()
         raise _Stop(value)
     dispatch[STOP[0]] = load_stop

 # Shorthands

 def _dump(obj, file, protocol=None, *, fix_imports=True):
     _Pickler(file, protocol, fix_imports=fix_imports).dump(obj)

 def _dumps(obj, protocol=None, *, fix_imports=True):
     f = io.BytesIO()
     _Pickler(f, protocol, fix_imports=fix_imports).dump(obj)
     res = f.getvalue()
     assert isinstance(res, bytes_types)
     return res

 def _load(file, *, fix_imports=True, encoding="ASCII", errors="strict"):
     return _Unpickler(file, fix_imports=fix_imports,
                      encoding=encoding, errors=errors).load()

 def _loads(s, *, fix_imports=True, encoding="ASCII", errors="strict"):
     if isinstance(s, str):
         raise TypeError("Can't load pickle from unicode string")
     file = io.BytesIO(s)
     return _Unpickler(file, fix_imports=fix_imports,
                       encoding=encoding, errors=errors).load()

 # Use the faster _pickle if possible
 try:
     from _pickle import (
         PickleError,
         PicklingError,
         UnpicklingError,
         Pickler,
         Unpickler,
         dump,
         dumps,
         load,
         loads
     )
 except ImportError:
     Pickler, Unpickler = _Pickler, _Unpickler
     dump, dumps, load, loads = _dump, _dumps, _load, _loads

 # Doctest
 def _test():
     import doctest
     return doctest.testmod()

 if __name__ == "__main__":
     import argparse
     parser = argparse.ArgumentParser(
         description='display contents of the pickle files')
     parser.add_argument(
         'pickle_file', type=argparse.FileType('br'),
         nargs='*', help='the pickle file')
     parser.add_argument(
         '-t', '--test', action='store_true',
         help='run self-test suite')
     parser.add_argument(
         '-v', action='store_true',
         help='run verbosely; only affects self-test run')
     args = parser.parse_args()
     if args.test:
         _test()
     else:
         if not args.pickle_file:
             parser.print_help()
         else:
             import pprint
             for f in args.pickle_file:
                 obj = load(f)
                 pprint.pprint(obj)

python:pickle