code: def check_ccl(process_group_backend: Optional[str]):
      """
      Check whether process group backend is None or 'ccl'.
  
      :param process_group_backend: process group backend
      """
      if process_group_backend is not None:
          invalidInputError(
              process_group_backend == "ccl",
              f"Process group backends supported now are None and 'ccl'",
              f" but got {process_group_backend}.",
          )
          pkg_name = ""
          try:
              if TORCH_VERSION_LESS_1_12:
                  pkg_name = "torch_ccl"
                  import torch_ccl
              else:
                  pkg_name = "oneccl_bindings_for_pytorch"
                  import oneccl_bindings_for_pytorch
          except Exception as _e:
              invalidInputError(
                  False,
                  f"Failed to import {pkg_name}, "
                  "maybe you should install it first: "
                  "pip install oneccl_bind_pt=<your pytroch version> -f "
                  "https://developer.intel.com/ipex-whl-stable-cpu",
              )
  
imports: from bigdl.nano.utils.common import invalidInputError
  from bigdl.nano.utils.pytorch import TORCH_VERSION_LESS_1_12
  from typing import Optional
label_desc: Use image node_id 1 for calling a global function with example usage: check_ccl(process_group_backend) without return types