perl 哈希 连接符

#!/usr/bin/perl -w

use strict;

my $test_1 = "AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA";
my $test_2 = "TTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT";

my %hash;

$hash{key} = $test_1;
print $hash{key}, "\n";

$hash{key} = $hash{key} . $test_2;
print $hash{key}, "\n";

AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAATTTTTTTTTTTTTTTTTTTTTTTTTTTTTTT