code: def test_cutoff_vocab(self):
      with tempfile.TemporaryDirectory() as tempdir:
          sample_file = os.path.join(tempdir, "t1.txt")
          with open(sample_file, "w", encoding="utf-8") as fout:
              fout.write(fake_text_1)
          sample_file = os.path.join(tempdir, "t2.txt.xz")
          with lzma.open(sample_file, "wt", encoding="utf-8") as fout:
              fout.write(fake_text_2)
  
          vocab = char_model.build_charlm_vocab(tempdir, cutoff=2)
  
      counts = Counter(fake_text_1) + Counter(fake_text_2)
      for letter, count in counts.most_common():
          if count < 2:
              assert letter not in vocab
          else:
              assert letter in vocab
  
imports: from collections import Counter
  import glob
  import lzma
  import os
  import tempfile
  import pytest
  from stanza.models import charlm
  from stanza.models.common import char_model
  from stanza.tests import TEST_MODELS_DIR
label_desc: Use image node_id 5 for calling the TestCharModel obj's underlying member method code with example usage: obj.test_cutoff_vocab() without return types