code: def test_index_converts_field_correctly(self):
      vocab = Vocabulary()
      sentence_index = vocab.add_token_to_namespace(
          "sentence", namespace="words"
      )
      capital_a_index = vocab.add_token_to_namespace(
          "A", namespace="words"
      )
      capital_a_char_index = vocab.add_token_to_namespace(
          "A", namespace="characters"
      )
      s_index = vocab.add_token_to_namespace(
          "s", namespace="characters"
      )
      e_index = vocab.add_token_to_namespace(
          "e", namespace="characters"
      )
      n_index = vocab.add_token_to_namespace(
          "n", namespace="characters"
      )
      t_index = vocab.add_token_to_namespace(
          "t", namespace="characters"
      )
      c_index = vocab.add_token_to_namespace(
          "c", namespace="characters"
      )
  
      field = TextField(
          [Token(t) for t in ["A", "sentence"]],
          {"words": SingleIdTokenIndexer(namespace="words")},
      )
      field.index(vocab)
      # pylint: disable=protected-access
      assert field._indexed_tokens["words"] == [
          capital_a_index,
          sentence_index,
      ]
  
      field1 = TextField(
          [Token(t) for t in ["A", "sentence"]],
          {
              "characters": TokenCharactersIndexer(
                  namespace="characters"
              )
          },
      )
      field1.index(vocab)
      assert field1._indexed_tokens["characters"] == [
          [capital_a_char_index],
          [
              s_index,
              e_index,
              n_index,
              t_index,
              e_index,
              n_index,
              c_index,
              e_index,
          ],
      ]
      field2 = TextField(
          [Token(t) for t in ["A", "sentence"]],
          token_indexers={
              "words": SingleIdTokenIndexer(namespace="words"),
              "characters": TokenCharactersIndexer(
                  namespace="characters"
              ),
          },
      )
      field2.index(vocab)
      assert field2._indexed_tokens["words"] == [
          capital_a_index,
          sentence_index,
      ]
      assert field2._indexed_tokens["characters"] == [
          [capital_a_char_index],
          [
              s_index,
              e_index,
              n_index,
              t_index,
              e_index,
              n_index,
              c_index,
              e_index,
          ],
      ]
  
imports: from __future__ import with_statement
  from __future__ import absolute_import
  from __future__ import print_function
  from collections import defaultdict
  import pytest
  import numpy
  from allennlp.data import Token, Vocabulary
  from allennlp.data.fields import TextField
  from allennlp.data.token_indexers import SingleIdTokenIndexer, TokenCharactersIndexer, TokenIndexer
  from allennlp.common.testing import AllenNlpTestCase
  from allennlp.common.checks import ConfigurationError
  from allennlp.common.util import pad_sequence_to_length
label_desc: Use image node_id 3 for calling the TestTextField obj's underlying member method code with example usage: obj.test_index_converts_field_correctly() without return types