code: def __check_stigma_words(self):
      if not self._stigma_words:
          raise ValueError(
              "Set of stigma words is empty. Please set attribute 'stigma_words' with collection of words."
          )
  
imports: from __future__ import absolute_import
  from __future__ import division, print_function, unicode_literals
  from collections import defaultdict
  from ..nlp.stemmers import null_stemmer
  from ._summarizer import AbstractSummarizer
  from .edmundson_cue import EdmundsonCueMethod
  from .edmundson_key import EdmundsonKeyMethod
  from .edmundson_title import EdmundsonTitleMethod
  from .edmundson_location import EdmundsonLocationMethod
label_desc: Use image node_id 20 for calling the EdmundsonSummarizer obj's underlying member method code with example usage: obj.__check_stigma_words() without return types