code: def testDifference(self):
      class Element(object):
          pass
  
      a = Element()
      b = Element()
      c = Element()
      set1 = object_identity.ObjectIdentitySet([a, b])
      set2 = object_identity.ObjectIdentitySet([b, c])
      diff_set = set1.difference(set2)
      self.assertIn(a, diff_set)
      self.assertNotIn(b, diff_set)
      self.assertNotIn(c, diff_set)
  
file_path: tensorflow/tensorflow/python/util/object_identity_test.py
imports: from tensorflow.python.platform import test
  from tensorflow.python.util import nest
  from tensorflow.python.util import object_identity
label_desc: Use image node_id 1 for calling the ObjectIdentitySetTest obj's underlying member method code with example usage: obj.testDifference() without return types