my $Sentence = "Answer to puzzle\n";
print "$Sentence\n";
my $Hex = unpack("H*",$Sentence);
print "$Hex\n";
# prints '416e7377657220746f2070757a7a6c650a'
my $Sentence2 = pack("H*",$Hex);
print "$Sentence2\n";
# prints 'Answer to puzzle'