code: def test_serialize_columns():
      serialized = serialize_columns(EXAMPLE_INPUT)
      # Verify that two layers are present
      assert serialized.get("a") and serialized.get("b")
      assert serialized["a"]["length"] == 3
      assert serialized["b"]["length"] == 3
      assert set(serialized.keys()) == set(
          EXPECTED_OUTPUT.keys()
      ), "Different layers in output and expectation"
      assert set(serialized["a"].keys()) == set(
          EXPECTED_OUTPUT["a"].keys()
      ), "Accessors different in output and expectation for layer a"
      assert set(serialized["b"].keys()) == set(
          EXPECTED_OUTPUT["b"].keys()
      ), "Accessors different in output and expectation for layer b"
  
      # Verify that data buffers are correct
      for layer_key in serialized.keys():
          layer_dict = serialized[layer_key]
          for accessor_name in layer_dict["attributes"].keys():
              buf0 = np.frombuffer(
                  layer_dict["attributes"][accessor_name]["value"],
                  layer_dict["attributes"][accessor_name]["dtype"],
              )
              buf1 = np.frombuffer(
                  EXPECTED_OUTPUT[layer_key]["attributes"][
                      accessor_name
                  ]["value"],
                  dtype=EXPECTED_OUTPUT[layer_key]["attributes"][
                      accessor_name
                  ]["dtype"],
              )
              assert np.array_equal(
                  buf0, buf1
              ), "Binary buffer contents differ for {} in {}".format(
                  accessor_name, layer_key
              )
              assert (
                  layer_dict["attributes"][accessor_name]["size"]
                  == EXPECTED_OUTPUT[layer_key]["attributes"][
                      accessor_name
                  ]["size"]
              ), "Size differs for {} in {}".format(
                  accessor_name, layer_key
              )
  
label_desc: Use image node_id 2 for calling a global function with example usage: test_serialize_columns() without return types