code: def default_dict_key(prefix: str) -> str:
      """Returns the default key to use with a dict associated with given prefix."""
      return util.KEY_SEPARATOR + prefix
  
file_path: model-analysis/tensorflow_model_analysis/eval_saved_model/util.py
imports: from typing import Any, Callable, List, Optional, Tuple
  import numpy
  import tensorflow
  from tensorflow import estimator
  from tensorflow_model_analysis.api import types
  from tensorflow_model_analysis.utils import util
  from tensorflow.core.example import example_pb2
label_desc: Use image node_id 1 for calling a global function with example usage: default_dict_key(prefix) and returns: unknown