code: def testNestFlatten(self):
      a = object_identity._ObjectIdentityWrapper("a")
      b = object_identity._ObjectIdentityWrapper("b")
      c = object_identity._ObjectIdentityWrapper("c")
      flat = tf.nest.flatten([[[(a, b)]], c])
      self.assertEqual(flat, [a, b, c])
  
file_path: agents/tf_agents/utils/object_identity_test.py
imports: from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  import tensorflow
  from tf_agents.utils import object_identity
label_desc: Use image node_id 2 for calling the ObjectIdentityWrapperTest obj's underlying member method code with example usage: obj.testNestFlatten() without return types