code: def test_create_vocabulary_single_token_small_most_frequent():
      data = pd.DataFrame(
          ["dog", "cat", "bird", "dog", "cat", "super cat"]
      )
      column = data[0]
  
      (
          vocab,
          str2idx,
          str2freq,
      ) = strings_utils.create_vocabulary_single_token(
          column, num_most_frequent=2
      )
  
      assert set(vocab) == {"dog", "cat", strings_utils.UNKNOWN_SYMBOL}
      assert str2idx[strings_utils.UNKNOWN_SYMBOL] == 0
      assert str2freq == {
          "dog": 2,
          "cat": 2,
          strings_utils.UNKNOWN_SYMBOL: 0,
      }
  
file_path: ludwig/tests/ludwig/utils/test_strings_utils.py
imports: from collections import defaultdict
  import numpy
  import pandas
  import pytest
  from ludwig.schema.features.preprocessing.text import TextPreprocessingConfig
  from ludwig.utils import strings_utils
label_desc: Use image node_id 10 for calling a global function with example usage: test_create_vocabulary_single_token_small_most_frequent() without return types