code: def test_doc_freq_one_doc(self):
      texts = [["human", "interface", "computer"]]
      d = Dictionary(texts)
      expected = {0: 1, 1: 1, 2: 1}
      self.assertEqual(d.dfs, expected)
  
imports: from collections.abc import Mapping
  from itertools import chain
  import logging
  import unittest
  import codecs
  import os
  import os.path
  import scipy
  import gensim
  from gensim.corpora import Dictionary
  from gensim.utils import to_utf8
  from gensim.test.utils import get_tmpfile, common_texts
label_desc: Use image node_id 2 for calling the TestDictionary obj's underlying member method code with example usage: obj.test_doc_freq_one_doc() without return types