class_docstr: tests Vocabulary Class
class_docstr_tok: ["tests","Vocabulary","Class"]
code: def test_lookup_recursive(self):
      self.assertEqual(
          self.vocab.lookup([["a", "b"], ["a", "c"]]),
          (("a", "b"), ("a", "<UNK>")),
      )
      self.assertEqual(
          self.vocab.lookup([["a", "b"], "c"]), (("a", "b"), "<UNK>")
      )
      self.assertEqual(
          self.vocab.lookup([[[[["a", "b"]]]]]), ((((("a", "b"),),),),)
      )
  
imports: import unittest
  from collections import Counter
  from timeit import timeit
  from nltk.lm import Vocabulary
label_desc: Use image node_id 14 for calling the NgramModelVocabularyTests obj's underlying member method code with example usage: obj.test_lookup_recursive() without return types