The command line invocation example
    perl -wMstrict -l  your_file.pl  GGGGaaaaaaCatttatatat  atatataaatttttATtcccc
was intended to show how to invoke a source code file (prepared as described in previous replies) and followed by two sequence strings  GGGGaaaaaaCatttatatat and  atatataaatttttATtcccc to be compared for reverse-complementarity. (BTW: I've tried this exact command line and it works.)