Also consider:

c:\@Work\Perl\monks\sierpinski>perl -wMstrict -le
"my $s = 'some string -- could be any length';
 ;;
 my $up = unpack 'a*', $s;
 $s eq $up or die 'A: not identity operation';
 ;;
 my $p = pack 'a*', $up;
 $s eq $p or die 'B: not identity operation';
 ;;
 print 'a-ok';
"
a-ok
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