code: def test_headers(self):
      details = "hmm"
      challenge = 'Bearer realm="https://example.com"'
      e1 = errors.UnauthenticatedError(details, challenge=challenge)
      e2 = errors.UnauthenticatedError(details, challenge=challenge)
      self.assertEqual(
          e1.headers,
          [("WWW-Authenticate", 'Bearer realm="https://example.com"')],
      )
      self.assertIsNot(e1.headers, e2.headers)
  
imports: from tensorboard import errors
  from tensorboard import test
label_desc: Use image node_id 4 for calling the UnauthenticatedErrorTest obj's underlying member method code with example usage: obj.test_headers() without return types