code: def test(self):
      input = torch.zeros(
          (1,), dtype=torch.half, device=torch.cuda.current_device()
      )
  
      (output,) = reduce_scatter_coalesced(
          [input], dist.get_world_group()
      )
  
      if dist.get_rank() == 0:
          assert output.shape == (1,)
          assert torch.allclose(output, torch.zeros_like(output))
      elif dist.get_rank() == 1:
          assert output.shape == (0,)
  
file_path: H2O/h2o_flexgen/benchmark/third_party/DeepSpeed/tests/unit/runtime/comm/test_coalesced_collectives.py
imports: import torch
  import deepspeed.comm
  from deepspeed.runtime.comm.coalesced_collectives import reduce_scatter_coalesced
  from unit.common import DistributedTest
label_desc: Use image node_id 1 for calling the TestReduceScatterCoalescedTensorSmallerThanWorldSize obj's underlying member method code with example usage: obj.test() without return types