code: def load_iterator_initializer_name(
      signature_def: tf.compat.v1.MetaGraphDef.SignatureDefEntry,
      graph: tf.Graph,
  ) -> Optional[types.TensorType]:
      """Loads iterator initializer name tensor from signature_def.inputs.
  
      Args:
        signature_def: SignatureDef to lookup initializer in.
        graph: TensorFlow graph to lookup the initializer in.
  
      Returns:
        Tensor containing iterator initializer op name or None if not used.
      """
      if (
          constants.SIGNATURE_DEF_ITERATOR_INITIALIZER_KEY
          in signature_def.inputs
      ):
          return tf.compat.v1.saved_model.utils.get_tensor_from_tensor_info(
              signature_def.inputs[
                  constants.SIGNATURE_DEF_ITERATOR_INITIALIZER_KEY
              ],
              graph,
          )
      return None
  
imports: import collections
  from typing import Dict, List, Optional, Tuple, Union
  import tensorflow
  from tensorflow_model_analysis.api import types
  from tensorflow_model_analysis.eval_saved_model import constants
  from tensorflow_model_analysis.eval_saved_model import encoding
  from tensorflow_model_analysis.eval_saved_model import util
  from google.protobuf import any_pb2
  from tensorflow.core.protobuf import meta_graph_pb2
label_desc: Use image node_id 6 for calling a global function with example usage: load_iterator_initializer_name(signature_def, graph) and returns: None, tf