code: def test_igdn_has_correct_output(self):
      x = tf.random.uniform((1, 2, 3, 4), dtype=tf.float32)
      y = gdn.GDN(inverse=True, rectify=False)(x)
      self.assertEqual(x.shape, y.shape)
      self.assertAllClose(y, x * (1 + 0.1 * abs(x)), rtol=0, atol=1e-6)
  
imports: import os
  from absl.testing import parameterized
  import tensorflow
  from tensorflow_compression.python.layers import gdn
  from tensorflow_compression.python.layers import parameters
label_desc: Use image node_id 6 for calling the GDNTest obj's underlying member method code with example usage: obj.test_igdn_has_correct_output() without return types