code: def voxel_test_sfn(data, msk, myrad, bcast):
      rad = bcast.rad
      # Check each point
      for subj in data:
          for _tr in range(subj.shape[3]):
              tr = subj[:, :, :, _tr]
              midpt = tr[rad, rad, rad]
              for d0 in range(tr.shape[0]):
                  for d1 in range(tr.shape[1]):
                      for d2 in range(tr.shape[2]):
                          assert np.array_equal(
                              tr[d0, d1, d2] - midpt,
                              np.array(
                                  [d0 - rad, d1 - rad, d2 - rad, 0]
                              ),
                          )
  
      # Determine midpoint
      midpt = data[0][rad, rad, rad, 0]
      midpt = (midpt[0], midpt[1], midpt[2])
  
      for d0 in range(msk.shape[0]):
          for d1 in range(msk.shape[1]):
              for d2 in range(msk.shape[2]):
                  pt = (
                      midpt[0] - rad + d0,
                      midpt[1] - rad + d1,
                      midpt[2] - rad + d2,
                  )
                  assert bcast.mask[pt] == msk[d0, d1, d2]
  
      # Return midpoint
      return midpt
  
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 9 for calling a global function with example usage: voxel_test_sfn(data, msk, myrad, bcast) and returns: midpt