code: def report_num_gpus(self):
      n_gpus = get_num_gpus()
      return n_gpus
  
imports: import cupy
  import logging
  import ray
  import ray.util.collective
  from ray.util.collective.types import Backend, ReduceOp
  from ray.util.collective.collective_group.nccl_util import get_num_gpus
  import torch
label_desc: Use image node_id 21 for calling the MultiGPUWorker obj's underlying member method code with example usage: obj.report_num_gpus() and returns: n_gpus