has 'input_line_number' => (
    traits  => [ 'Counter' ],
    is      => 'ro',
    isa     => 'Int',
    default => 0,
    handles => {
        'inc_line_number'      => 'inc',
        'dec_line_number'      => 'dec',
        '_reset_line_number'   => 'reset',                
        'skip_ahead_two_lines' => [ 'inc' => 2 ]
    }
);