sub invert{
    #2345678901234567890123456789012345678
    $_=pack'C*',1..255;s/[\Q$_[0]\E]//g,$_
}
print invert('/just Another Bug to Fix!/');

# 35 strokes using @_ hack

sub invert{
    #2345678901234567890123456789012345
    $_=pack'C*',1..255;s/[\Q@_\E]//g,$_
}
print invert('/just Another Bug to Fix!/');