class_docstr: Test remove digits.
class_docstr_tok: ["Test","remove","digits","."]
code: def test_tokenize_split_punctuation(self):
      s = pd.Series(["ready. set, go!"])
      s_true = pd.Series([["ready", ".", "set", ",", "go", "!"]])
      self.assertEqual(preprocessing.tokenize(s), s_true)
  
imports: import string
  import pytest
  import pandas
  import numpy
  import doctest
  from texthero import preprocessing, stopwords
  from .None import PandasTestCase
  import warnings
label_desc: Use image node_id 20 for calling the TestPreprocessing obj's underlying member method code with example usage: obj.test_tokenize_split_punctuation() without return types