code: def reduce_mean(tensor):
      """ "Obtain the mean of tensor on different GPUs."""
      if not (dist.is_available() and dist.is_initialized()):
          return tensor
      tensor = tensor.clone()
      dist.all_reduce(
          tensor.div_(dist.get_world_size()), op=dist.ReduceOp.SUM
      )
      return tensor
  
file_path: mmdetection/mmdet/utils/dist_utils.py
imports: import functools
  import pickle
  import warnings
  from collections import OrderedDict
  import numpy
  import torch
  import torch.distributed
  from mmengine.dist import get_dist_info
  from torch._utils import _flatten_dense_tensors, _take_tensors, _unflatten_dense_tensors
label_desc: Use image node_id 3 for calling a global function with example usage: reduce_mean(tensor) and returns: tensor, tensor