code: def test_method(self):
      o1 = Counter()
      o2 = Counter()
      for _ in range(10):
          o1.increment()
          o2.increment()
  
      self.assertEqual(o1.call_count, 1)
      self.assertEqual(o2.call_count, 1)
  
imports: import pickle
  from absl.testing import absltest
  from absl.testing import parameterized
  from sonnet.src import once
label_desc: Use image node_id 4 for calling the OnceTest obj's underlying member method code with example usage: obj.test_method() without return types