{
    rest => $next_node,
    first => $data
}

##</code><code>##

sub value {
    my ($self) = @_;
    my @value = ($self->{first},
                 $self->{rest} ? $self->{rest}->value : ());
    return @value;
}

##</code><code>##

sub value {
    my ($self) = @_;
    return ($self->{first},
            $self->{rest} ? $self->{rest}->value : ())
}

##</code><code>##

sub value {
    my ($self) = @_;
    return @{[$self->{first},
              $self->{rest} ? $self->{rest}->value : ()]};
}