code: def testisSubtypeOf(self):
      spec = resource_variable_ops.VariableSpec(
          [1, 3], dtypes.float32, False, 1
      )
      spec2 = resource_variable_ops.VariableSpec(
          None, dtypes.float32, False, 1
      )
      self.assertTrue(spec.is_subtype_of(spec2))
      self.assertFalse(spec2.is_subtype_of(spec))
      spec3 = resource_variable_ops.VariableSpec(
          None, dtypes.float32, False
      )
      with self.assertRaises(NotImplementedError):
          spec.is_subtype_of(spec3)
      with self.assertRaises(NotImplementedError):
          spec3.is_subtype_of(spec)
  
imports: from absl.testing import parameterized
  import numpy
  from tensorflow.python.eager import context
  from tensorflow.python.framework import constant_op
  from tensorflow.python.framework import dtypes
  from tensorflow.python.framework import ops
  from tensorflow.python.framework import tensor_spec
  from tensorflow.python.framework import test_util
  from tensorflow.python.ops import array_ops
  from tensorflow.python.ops import resource_variable_ops
  from tensorflow.python.platform import test
  from tensorflow.python.util import nest
label_desc: Use image node_id 13 for calling the VariableSpecTest obj's underlying member method code with example usage: obj.testisSubtypeOf() without return types