class_docstr: Abstraction which performs slot filling
  
  A custom slot filler must inherit this class to be used in a
  :class:`.ProbabilisticIntentParser`
code: def unit_name(cls):  # pylint:disable=no-self-argument
      return SlotFiller.registered_name(cls)
  
file_path: snips-nlu/snips_nlu/slot_filler/slot_filler.py
imports: from abc import abstractmethod, ABCMeta
  from future.utils import with_metaclass
  from snips_nlu.common.abc_utils import classproperty
  from snips_nlu.pipeline.processing_unit import ProcessingUnit
label_desc: Use image node_id 1 for calling the SlotFiller obj's underlying member method code with example usage: obj.unit_name(cls) and returns: SlotFiller