code: def test_returns_none_legal(self):
      self.assertFunctionMatchesEager(if_returns_none, True)
      self.assertFunctionMatchesEager(if_else_returns_none, False)
      self.assertFunctionMatchesEager(else_returns_none, False)
  
imports: import itertools
  import re
  from absl.testing import parameterized
  import tensorflow
  from tensorflow.python.autograph.tests import reference_test_base
label_desc: Use image node_id 6 for calling the ReferenceTest obj's underlying member method code with example usage: obj.test_returns_none_legal() without return types