code: def testDTypeSubtypes(self):
      self.assertTrue(dtypes.string.is_subtype_of(dtypes.string))
      self.assertFalse(dtypes.string.is_subtype_of(dtypes.uint32))
      self.assertTrue(dtypes.uint64.is_subtype_of(dtypes.uint64))
  
imports: from absl.testing import parameterized
  import numpy
  from tensorflow.python.framework import _dtypes
  from tensorflow.core.framework import types_pb2
  from tensorflow.core.function import trace_type
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import test_util
  from tensorflow.python.platform import googletest
label_desc: Use image node_id 23 for calling the TypesTest obj's underlying member method code with example usage: obj.testDTypeSubtypes() without return types