code: def test_three_sentences():
      document = build_document(
          (
              "wa s s s wa s s s wa",
              "wb s wb s wb s s s s s s s s s wb",
              "wc s s wc s s wc",
          )
      )
      summarizer = LuhnSummarizer()
      summarizer.stop_words = ("s",)
  
      returned = summarizer(document, 1)
      assert list(map(to_unicode, returned)) == [
          "wb s wb s wb s s s s s s s s s wb",
      ]
  
      returned = summarizer(document, 2)
      assert list(map(to_unicode, returned)) == [
          "wb s wb s wb s s s s s s s s s wb",
          "wc s s wc s s wc",
      ]
  
      returned = summarizer(document, 3)
      assert list(map(to_unicode, returned)) == [
          "wa s s s wa s s s wa",
          "wb s wb s wb s s s s s s s s s wb",
          "wc s s wc s s wc",
      ]
  
file_path: sumy/tests/test_summarizers/test_luhn.py
imports: from __future__ import absolute_import, division, print_function, unicode_literals
  from sumy._compat import to_unicode
  from sumy.nlp.stemmers.czech import stem_word
  from sumy.nlp.tokenizers import Tokenizer
  from sumy.parsers.plaintext import PlaintextParser
  from sumy.summarizers.luhn import LuhnSummarizer
  from sumy.utils import get_stop_words
  from ..utils import build_document
label_desc: Use image node_id 5 for calling a global function with example usage: test_three_sentences() without return types