code: def testClear(self):
      a = object()
      b = object()
      set1 = object_identity.ObjectIdentitySet([a, b])
      set1.clear()
      self.assertLen(set1, 0)
  
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 3 for calling the ObjectIdentitySetTest obj's underlying member method code with example usage: obj.testClear() without return types