code: def testGetValueIndex(self):
      typenames = (
          "SHORT",
          "INT",
          "LONG",
          "FLOAT",
          "DOUBLE",
          "LONG_DOUBLE",
      )
      value_types = [getattr(MPI, f"{attr}") for attr in typenames]
      pair_types = [getattr(MPI, f"{attr}_INT") for attr in typenames]
      for value, pair in zip(value_types, pair_types):
          result = MPI.Datatype.Get_value_index(value, MPI.INT)
          self.assertEqual(result, pair)
      for value in value_types:
          result = MPI.Datatype.Get_value_index(value, MPI.FLOAT)
          self.assertEqual(result, MPI.DATATYPE_NULL)
  
imports: from mpi4py import MPI
  import mpiunittest
  import struct
label_desc: Use image node_id 6 for calling the TestDatatype obj's underlying member method code with example usage: obj.testGetValueIndex() without return types