#!/usr/bin/env perl
use strict;
use warnings;

sub _validate_arguments {
    my ( $first_arg, $second_arg ) = @_;
    croak "Called without arguments." if @_ < 1;
    croak "Called with " . scalar @_ . " arguments. Expected arguments: 1 or 2." if @_ > 2;
    croak "The first argument is not defined." if ! defined $first_arg;
    ...
    ...
    carp "The first argument refers to an empty list!" if ! @$first_arg;
    return ( $first_arg, $second_arg );
}

sub my_function {
    my ( $first_arg, $second_arg ) = &_validate_arguments;
    return if ! @$first_arg;
    ...
    ...
}