def default_features_factories():
    """These are the default features used by the :class:`.CRFSlotFiller`
        objects"""
    from snips_nlu.slot_filler.crf_utils import TaggingScheme
    from snips_nlu.slot_filler.feature_factory import NgramFactory, IsDigitFactory, IsFirstFactory, IsLastFactory, ShapeNgramFactory, CustomEntityMatchFactory, BuiltinEntityMatchFactory
    return [{'args': {'common_words_gazetteer_name': None, 'use_stemming': 
        False, 'n': 1}, 'factory_name': NgramFactory.name, 'offsets': [-2, 
        -1, 0, 1, 2]}, {'args': {'common_words_gazetteer_name': None,
        'use_stemming': False, 'n': 2}, 'factory_name': NgramFactory.name,
        'offsets': [-2, 1]}, {'args': {}, 'factory_name': IsDigitFactory.
        name, 'offsets': [-1, 0, 1]}, {'args': {}, 'factory_name':
        IsFirstFactory.name, 'offsets': [-2, -1, 0]}, {'args': {},
        'factory_name': IsLastFactory.name, 'offsets': [0, 1, 2]}, {'args':
        {'n': 1}, 'factory_name': ShapeNgramFactory.name, 'offsets': [0]},
        {'args': {'n': 2}, 'factory_name': ShapeNgramFactory.name,
        'offsets': [-1, 0]}, {'args': {'n': 3}, 'factory_name':
        ShapeNgramFactory.name, 'offsets': [-1]}, {'args': {'use_stemming':
        False, 'tagging_scheme_code': TaggingScheme.BILOU.value},
        'factory_name': CustomEntityMatchFactory.name, 'offsets': [-2, -1, 
        0], 'drop_out': 0.5}, {'args': {'tagging_scheme_code':
        TaggingScheme.BIO.value}, 'factory_name': BuiltinEntityMatchFactory
        .name, 'offsets': [-2, -1, 0]}]
