code: def init_group(
      self, world_size, rank, backend=Backend.NCCL, group_name="default"
  ):
      col.init_collective_group(world_size, rank, backend, group_name)
      return True
  
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 3 for calling the Worker obj's underlying member method code with example usage: obj.init_group(world_size, rank, backend, group_name) and returns: True