class_docstr: Source: https://github.com/adamfabish/Reduction
code: def _to_words_set(self, sentence):
      words = map(self.normalize_word, sentence.words)
      return [
          self.stem_word(w) for w in words if w not in self._stop_words
      ]
  
file_path: sumy/sumy/summarizers/reduction.py
imports: from __future__ import absolute_import
  from __future__ import division, print_function, unicode_literals
  import math
  from itertools import combinations
  from collections import defaultdict
  from ._summarizer import AbstractSummarizer
label_desc: Use image node_id 5 for calling the ReductionSummarizer obj's underlying member method code with example usage: obj._to_words_set(sentence) and returns: unknown