code: def test_scatter_large_dataset_flat():
      mpi_comm = mpi4py.MPI.COMM_WORLD
      communicator = FlatCommunicator(mpi_comm)
  
      # This test only runs when comm.size >= 2.
      if communicator.size == 1:
          pytest.skip("This test is for multinode")
  
      scatter_large_data(communicator)
  
imports: from __future__ import with_statement
  import itertools
  import unittest
  import mpi4py.MPI
  import numpy
  import pytest
  from chainer import testing
  import chainermn
  from chainermn.communicators.flat_communicator import FlatCommunicator
  from chainermn.communicators.naive_communicator import NaiveCommunicator
  import chainerx
label_desc: Use image node_id 3 for calling a global function with example usage: test_scatter_large_dataset_flat() without return types