public static <InputT, OutputT> MapElements<InputT, OutputT> via(
      final InferableFunction<InputT, OutputT> fn) {
    return new MapElements<>(fn, fn.getInputTypeDescriptor(), fn.getOutputTypeDescriptor());
  }
@Test
  public void testSimpleFunctionClassDisplayData() {
    SimpleFunction<?, ?> simpleFn =
        new SimpleFunction<Integer, Integer>() {
          @Override
          public Integer apply(Integer input) {
            return input;
          }
        };

    MapElements<?, ?> simpleMap = MapElements.via(simpleFn);
    assertThat(DisplayData.from(simpleMap), hasDisplayItem("class", simpleFn.getClass()));
  }