code: def testF77(self):
      for mt in mpif77types:
          if mt == MPI.DATATYPE_NULL:
              continue
          if mt.Get_size() == 0:
              continue
          dt = tonumpy(mt)
          if np_dtype is not None:
              self.assertEqual(dt.itemsize, mt.extent)
  
imports: from mpi4py import MPI
  from mpi4py.util.dtlib import from_numpy_dtype
  from mpi4py.util.dtlib import to_numpy_dtype
  import sys, os
  import itertools
label_desc: Use image node_id 15 for calling the TestUtilDTLib obj's underlying member method code with example usage: obj.testF77() without return types