Speaking of signatures, Perl 5.20 introduced the concept in an experimental feature in 2015, and I’m only just getting around to trying it. Prior we would have done this:

sub sumificate {
    my ($first, $second) = @_;
    return $first + $second;

Or this for a single parameter:

sub printificate {
    my $message = shift;
    return $message;

Now we can do this:

use feature qw(say signatures);
no warnings qw(experimental::signatures);    
sub sumificate($first, $second) {
    return $first + $second;

This is compatible with use strict, even without my on the parameters which is a nice shorthand. The script is in my lunchbox if you want to give it a try.