code: def _make_key(prefix: str, category: str, key: str):
      """Generate a binary key for the given category and key.
  
      Args:
          prefix: Prefix
          category: The category of the item
          key: The unique identifier for the item
  
      Returns:
          The key to use for storing a the value.
      """
      return (
          b"TuneRegistry:"
          + prefix.encode("ascii")
          + b":"
          + category.encode("ascii")
          + b"/"
          + key.encode("ascii")
      )
  
imports: import atexit
  import logging
  from functools import partial
  from types import FunctionType
  from typing import Callable, Optional, Type, Union
  import ray
  import ray.cloudpickle
  from ray.experimental.internal_kv import _internal_kv_get, _internal_kv_initialized, _internal_kv_put, _internal_kv_del
  from ray.tune.error import TuneError
  from ray.util.annotations import DeveloperAPI
label_desc: Use image node_id 15 for calling a global function with example usage: _make_key(prefix, category, key) and returns: unknown