def METHOD_NAME(features):
    features.default_features.append('sansserif')
    """
    Registering the `sansserif` feature, which uses the `SANSSERIF` Draft.js entity type,
    and is stored as HTML with a `<span>` tag.
    """
    feature_name = 'sansserif'
    type_ = 'SANSSERIF'
    control = {
        'type': type_,
        'label': 'SS',
        'description': 'Sans Serif font',
    }
    features.register_editor_plugin(
        'draftail', feature_name, draftail_features.EntityFeature(control)
    )
    features.register_converter_rule('contentstate', feature_name, {
        # Call register_converter_rule to register the content transformation conversion
        'from_database_format': {'span': sansserif.SansserifEntityElementHandler(type_)},
        'to_database_format': {'entity_decorators': {type_: sansserif.sansserif_entity_decorator}},
    })