code: def do_reduce(
      self, group_name="default", dst_rank=0, op=ReduceOp.SUM
  ):
      col.reduce(self.buffer, dst_rank, group_name, op)
      return self.buffer
  
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 8 for calling the Worker obj's underlying member method code with example usage: obj.do_reduce(group_name, dst_rank, op) and returns: self