code: def testVector(self):
      for dtype in datatypes:
          for count in range(5):
              for blocklength in range(5):
                  for stride in range(5):
                      factory = MPI.Datatype.Create_vector
                      args = (count, blocklength, stride)
                      self.check(dtype, factory, *args)
  
imports: from mpi4py import MPI
  import mpiunittest
  import struct
label_desc: Use image node_id 6 for calling the BaseTestDatatypeCreateMixin obj's underlying member method code with example usage: obj.testVector() without return types