75.pl

package Photo;
use Moose;

has 'likes' => (
    is => 'rw',
    clearer => 'unpublish',
    predicate => 'is_published',
);

sub publish {
    my $self = shift;
    $self->likes ( 0 );
}

sub like {
    my $self = shift;

    die 'Cannot like an Unpublished photo'
        if ! $self->is_published;

    $self->likes ( $self->likes + 1 );
}


package main;

my $profile = Photo->new;
$profile->publish;
$profile->like;
$profile->like;

warn $profile->dump;