code: def test_returns_none_illegal(self, target, c):
      c = tf.constant(c)
      with self.assertRaisesRegex(
          ValueError, re.compile("'i' is None", re.DOTALL)
      ):
          tf.function(target)(c)
  
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 7 for calling the ReferenceTest obj's underlying member method code with example usage: obj.test_returns_none_illegal(target, c) without return types