Safari Books Online is a digital library providing on-demand subscription access to thousands of learning resources.
Some people have habits left over from the old C-programmer style, where they return a success code after every function. For instance, to signal an error from a subroutine, they might return undef:
sub do_work {
my $task = shift;
if ( $task < 0 ) {
return; # error, returning undef
}
...;
}