class_docstr: A ``TokenIndexer`` determines how string tokens get represented as arrays of indices in a model.
  This class both converts strings into numerical values, with the help of a
  :class:`~allennlp.data.vocabulary.Vocabulary`, and it produces actual arrays.
  
  Tokens can be represented as single IDs (e.g., the word "cat" gets represented by the number
  34), or as lists of character IDs (e.g., "cat" gets represented by the numbers [23, 10, 18]),
  or in some other way that you can come up with (e.g., if you have some structured input you
  want to represent in a special way in your data arrays, you can do that here).
docstr: Return a list of the keys this indexer return from ``tokens_to_indices``.
code: def get_keys(self, index_name):
      """
      Return a list of the keys this indexer return from ``tokens_to_indices``.
      """
      # pylint: disable=no-self-use
      return [index_name]
  
file_path: magnitude/pymagnitude/third_party/allennlp/data/token_indexers/token_indexer.py
imports: from __future__ import absolute_import
  from allennlp.common import Registrable
  from allennlp.data.tokenizers.token import Token
  from allennlp.data.vocabulary import Vocabulary
label_desc: Use image node_id 6 for calling the TokenIndexer obj's underlying member method code with example usage: obj.get_keys(index_name) and returns: list