@Test
void composeToInt() {

    final ToInt<String> toInt = String::length;
    final ComposeToInt<String, String, ToInt<String>> composeToInt =
            (ComposeToInt<String, String, ToInt<String>>)
                    ComposedUtil.composeToInt(Function.identity(), toInt);
    assertNotNull(composeToInt.firstStep());
    assertNotNull(composeToInt.secondStep());
    assertNull(composeToInt.apply(null));
    assertNotNull(composeToInt.apply("test"));
}