code: def _NcclAllReduce(nccl_fun, tensors, devices):
      return nccl_fun(_DeviceTensors(tensors, devices))
  
imports: from functools import partial
  import numpy
  from tensorflow.python.framework import errors
  from tensorflow.python.framework import ops
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import gradients
  from tensorflow.python.ops import nccl_ops
  from tensorflow.python.platform import test
label_desc: Use image node_id 2 for calling a global function with example usage: _NcclAllReduce(nccl_fun, tensors, devices) and returns: nccl_fun