code: def testLiteralSupertypes(self):
      literal_a = default_types.Literal(1)
      literal_b = default_types.Literal(2)
      literal_c = default_types.Literal(1)
  
      self.assertEqual(
          literal_a, literal_a.most_specific_common_supertype([])
      )
      self.assertEqual(
          literal_a,
          literal_a.most_specific_common_supertype([literal_a]),
      )
      self.assertEqual(
          literal_a,
          literal_a.most_specific_common_supertype([literal_c]),
      )
      self.assertIsNone(
          literal_a.most_specific_common_supertype([literal_b])
      )
  
imports: import collections
  from tensorflow.core.function.trace_type import default_types
  from tensorflow.core.function.trace_type import serialization
  from tensorflow.python.platform import test
  from tensorflow.python.types import trace
label_desc: Use image node_id 2 for calling the DefaultTypesTest obj's underlying member method code with example usage: obj.testLiteralSupertypes() without return types