code: def validate_trainable(trainable_name):
      if not _has_trainable(trainable_name):
          # Make sure everything rllib-related is registered.
          from ray.rllib import _register_all
  
          _register_all()
          if not _has_trainable(trainable_name):
              raise TuneError("Unknown trainable: " + trainable_name)
  
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 3 for calling a global function with example usage: validate_trainable(trainable_name) without return types