code: def merge_things(self, inputs):
      self.merge_artifacts(
          inputs,
      )
  
      # Ensure that everything we expect is passed down
      assert_equals(self.non_modified_passdown, "a")
      for i, _ in enumerate(inputs):
          assert_equals(getattr(self, "var%d" % (i)), i)
  
imports: from metaflow_test import MetaflowTest, ExpectationFailed, steps
label_desc: Use image node_id 3 for calling the MergeArtifactsPropagationTest obj's underlying member method code with example usage: obj.merge_things(inputs) without return types