our @ISA = qw(
    Collection::Bounded
    Collection::Unique
    Collection::Generic
);

##</code><code>##

sub add {
    my $self = shift;
    my $thing = shift;

    return undef if $self->contains($thing);
    return $self->SUPER::add($thing);
}

##</code><code>##

sub add {
    my $self = shift;
    my $thing = shift;

    my $collection = $self->{collection};
    return undef if $collection->contains($thing);

    return $collection->add($thing);
}

##</code><code>##

sub AUTOLOAD {
    my $self = shift;
    my $func = our $AUTOLOAD;

    $func =~ s/.*:://;
    return $self->{collection}->$func;
}