has tag_formatter => (
    is => 'ro',
    handles => [ qw( format_tag escape filter link_prefixes)],
    required => 1,
    weak_ref => 1,  # normally points back to parent Creole object
    );

 has config_keeper => (
    is => 'ro',
    handles => [ qw( placeholder_callback link_mapper image_mapper)],
    required => 1,
    weak_ref => 1,  # normally points back to parent Creole object
    );