code: def test_str(self):
      self.assertEqual(str(Metric("name")), "name")
      self.assertEqual(str(Metric("name", 10)), "name(10)")
  
imports: from absl.testing import parameterized
  import pipeline_dp
  from pipeline_dp import budget_accounting, aggregate_params
label_desc: Use image node_id 2 for calling the MetricsTest obj's underlying member method code with example usage: obj.test_str() without return types