code: def test_indexed_string_callable(self):
      s = "aabbccddaa"
  
      def tokenizer(string):
          return [
              string[i] + string[i + 1]
              for i in range(0, len(string) - 1, 2)
          ]
  
      tokenized_string = np.array(["aa", "bb", "cc", "dd", "aa"])
      inverse_vocab = ["aa", "bb", "cc", "dd"]
      start_positions = [0, 2, 4, 6, 8]
      positions = [[0, 4], [1], [2], [3]]
      indexed_string = IndexedString(s, tokenizer)
  
      self.assertTrue(
          np.array_equal(indexed_string.as_np, tokenized_string)
      )
      self.assertTrue(
          np.array_equal(indexed_string.string_start, start_positions)
      )
      self.assertTrue(indexed_string.inverse_vocab == inverse_vocab)
      self.assertTrue(
          np.array_equal(indexed_string.positions, positions)
      )
  
imports: import re
  import unittest
  import sklearn
  from sklearn.datasets import fetch_20newsgroups
  from sklearn.feature_extraction.text import TfidfVectorizer
  from sklearn.metrics import f1_score
  from sklearn.naive_bayes import MultinomialNB
  from sklearn.pipeline import make_pipeline
  import numpy
  from lime.lime_text import LimeTextExplainer
  from lime.lime_text import IndexedCharacters, IndexedString
label_desc: Use image node_id 7 for calling the TestLimeText obj's underlying member method code with example usage: obj.test_indexed_string_callable() and returns: unknown