code: def load_op_from_signature_def(signature_def, key, import_scope=None):
      """Load an Op from a SignatureDef created by op_signature_def().
  
      Args:
        signature_def: a SignatureDef proto
        key: string key to op in the SignatureDef outputs.
        import_scope: Scope used to import the op
  
      Returns:
        Op (or possibly Tensor) in the graph with the same name as saved in the
          SignatureDef.
  
      Raises:
        NotFoundError: If the op could not be found in the graph.
      """
      tensor_info = signature_def.outputs[key]
      try:
          # The init and train ops are not strictly enforced to be operations, so
          # retrieve any graph element (can be either op or tensor).
          return utils.get_element_from_tensor_info(
              tensor_info, import_scope=import_scope
          )
      except KeyError:
          raise errors.NotFoundError(
              None,
              None,
              f'The key "{key}" could not be found in the graph. Please make sure the'
              " SavedModel was created by the internal _SavedModelBuilder. If you "
              "are using the public API, please make sure the SignatureDef in the "
              f'SavedModel does not contain the key "{key}".',
          )
  
imports: from tensorflow.core.framework import types_pb2
  from tensorflow.core.protobuf import meta_graph_pb2
  from tensorflow.python.framework import errors
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import tensor
  from tensorflow.python.framework import tensor_util
  from tensorflow.python.saved_model import signature_constants
  from tensorflow.python.saved_model import utils_impl
  from tensorflow.python.util import deprecation
  from tensorflow.python.util.tf_export import tf_export
label_desc: Use image node_id 13 for calling a global function with example usage: load_op_from_signature_def(signature_def, key, import_scope) and returns: utils