def sum(items): head, *tails = items return head + sum(tails) if tails else head # 最后一句有点像三目运算符,如果tails为真,则执行前面的sum(tails),否则执行后面的head num_list = [1,2,3,4,5,6,7,8,9] print(sum(num_list)) 参考资料: Python Cookbook, 3rd edition, by David Beazley and Brian…