I love Perlmonks but Google is good for searching too, for example a search for "perl bioinformatics cpan reverse complement" yielded this page, which appears to "calculate the reverse complement of a strand of DNA" ... whatever that is. :)

L-LL-L--L-LL-L--L-LL-L--
-R--R-RR-R--R-RR-R--R-RR
B--B--B--B--B--B--B--B--
H---H---H---H---H---H---
(the triplet paradiddle with high-hat)