code: def test_stop_words_correctly_removed():
      summarizer = ReductionSummarizer()
      summarizer.stop_words = ["stop", "Halt", "SHUT", "HmMm"]
  
      document = build_document(
          (
              "stop halt shut hmmm",
              "Stop Halt Shut Hmmm",
          ),
          (
              "StOp HaLt ShUt HmMm",
              "STOP HALT SHUT HMMM",
          ),
          (
              "Some relevant sentence",
              "Some moRe releVant sentEnce",
          ),
      )
      sentences = document.sentences
  
      expected = []
      returned = summarizer._to_words_set(sentences[0])
      assert expected == returned
      returned = summarizer._to_words_set(sentences[1])
      assert expected == returned
      returned = summarizer._to_words_set(sentences[2])
      assert expected == returned
      returned = summarizer._to_words_set(sentences[3])
      assert expected == returned
  
      expected = ["some", "relevant", "sentence"]
      returned = summarizer._to_words_set(sentences[4])
      assert expected == returned
      expected = ["some", "more", "relevant", "sentence"]
      returned = summarizer._to_words_set(sentences[5])
      assert expected == returned
  
file_path: sumy/tests/test_summarizers/test_reduction.py
imports: from __future__ import absolute_import
  from __future__ import division, print_function, unicode_literals
  from sumy.summarizers.reduction import ReductionSummarizer
  from sumy.nlp.stemmers import Stemmer
  from sumy._compat import to_unicode
  from ..utils import build_document
label_desc: Use image node_id 4 for calling a global function with example usage: test_stop_words_correctly_removed() without return types