code: def test_single_proc_single_dev(self):
      comms = nccl.NcclCommunicator.initAll(1)
      nccl.groupStart()
      for comm in comms:
          cuda.Device(comm.device_id()).use()
          sendbuf = cupy.arange(10)
          recvbuf = cupy.zeros_like(sendbuf)
          comm.allReduce(
              sendbuf.data.ptr,
              recvbuf.data.ptr,
              10,
              nccl.NCCL_INT64,
              nccl.NCCL_SUM,
              cuda.Stream.null.ptr,
          )
      nccl.groupEnd()
      assert cupy.allclose(sendbuf, recvbuf)
  
file_path: cupy/tests/cupy_tests/cuda_tests/test_nccl.py
imports: import pickle
  import unittest
  import cupy
  from cupy import cuda
  from cupy.cuda import nccl
  from cupy import testing
label_desc: Use image node_id 5 for calling the TestNCCL obj's underlying member method code with example usage: obj.test_single_proc_single_dev() without return types