code: def test_small_vocab(self):
      corpus = "The quick brown fox jumps over the lazy dog"
      token_counts = collections.Counter(corpus.split(" "))
      alphabet = set(corpus) - {" "}
  
      encoder = text_encoder.SubwordTextEncoder.build_to_target_size(
          10, token_counts, 2, 10
      )
  
      # All vocabulary elements are in the alphabet and subtoken strings even
      # if we requested a smaller vocabulary to assure all expected strings
      # are encodable.
      self.assertTrue(alphabet.issubset(encoder._alphabet))
      for a in alphabet:
          self.assertIn(a, encoder.all_subtoken_strings)
  
imports: import collections
  import io
  import os
  import random
  import shutil
  import string
  import mock
  from six.moves import range
  import tensorflow.compat.v1
  from trax.data import text_encoder
label_desc: Use image node_id 4 for calling the SubwordTextEncoderTest obj's underlying member method code with example usage: obj.test_small_vocab() without return types