imap <F3>  use Data::Dumper; warn Dumper(  );^[hhi

after several years of using Dumper() like this i wrote a much more useful macro (see my other post).
forgetting Dumper() statements in code and finding the right ones to comment out can be really annoying. by using the Dump() method and variable names (Data::Dumper->Dump([\$test], ['test'])) you can debug much more sophisticated.