code: def test_searchlight_with_cube_poolsize_1():
      sl = Searchlight(sl_rad=3)
      comm = MPI.COMM_WORLD
      rank = comm.rank
      size = comm.size
      dim0, dim1, dim2 = (50, 50, 50)
      ntr = 30
      nsubj = 3
      mask = np.zeros((dim0, dim1, dim2), dtype=bool)
      data = [
          np.empty((dim0, dim1, dim2, ntr), dtype=object)
          if i % size == rank
          else None
          for i in range(0, nsubj)
      ]
  
      # Put a spot in the mask
      mask[10:17, 10:17, 10:17] = True
  
      sl.distribute(data, mask)
      global_outputs = sl.run_searchlight(cube_sfn, pool_size=1)
  
      if rank == 0:
          assert global_outputs[13, 13, 13] == 1.0
          global_outputs[13, 13, 13] = None
  
          for i in range(global_outputs.shape[0]):
              for j in range(global_outputs.shape[1]):
                  for k in range(global_outputs.shape[2]):
                      assert global_outputs[i, j, k] is None
  
file_path: brainiak/tests/searchlight/test_searchlight.py
imports: from collections import namedtuple
  import numpy
  from mpi4py import MPI
  import conftest
  from brainiak.searchlight.searchlight import Searchlight
  from brainiak.searchlight.searchlight import Diamond, Ball
label_desc: Use image node_id 3 for calling a global function with example usage: test_searchlight_with_cube_poolsize_1() without return types