code: def request_is_valid(item):
      """Check if an item is a valid request value (and not an alias).
  
      Parameters
      ----------
      item : object
          The given item to be checked.
  
      Returns
      -------
      result : bool
          Whether the given item is valid.
      """
      return item in VALID_REQUEST_VALUES
  
imports: import inspect
  from collections import namedtuple
  from copy import deepcopy
  from typing import TYPE_CHECKING, Optional, Union
  from warnings import warn
  from ..None import get_config
  from ..exceptions import UnsetMetadataPassedError
  from ._bunch import Bunch
label_desc: Use image node_id 5 for calling a global function with example usage: request_is_valid(item) and returns: unknown