gistfile1.txt

sub custom_commands {
    my $self = shift;
    return ($self->custom_commands, "helloworld";
}

sub do_custom_command {
    my $self = shift;
    my $command = shift;

    if ($command eq 'helloworld') {
        print "Hello, world!\n";
        return;
    }
    $self->SUPER::do_custom_command($command, @_);
}