class_docstr: tests Vocabulary Class
class_docstr_tok: ["tests","Vocabulary","Class"]
code: def test_unable_to_change_cutoff(self):
      with self.assertRaises(AttributeError):
          self.vocab.cutoff = 3
  
imports: import unittest
  from collections import Counter
  from timeit import timeit
  from nltk.lm import Vocabulary
label_desc: Use image node_id 4 for calling the NgramModelVocabularyTests obj's underlying member method code with example usage: obj.test_unable_to_change_cutoff() without return types