static <A> Cl<Class<? extends A>> singleArgumentMethodTypesSubclassing(O object, S methodName, Class<A> type) {
  L<Method> methods = singleArgumentMethods(findMethodsNamed_nonSynthetic(object, methodName));
  ret mapNonNulls(methods, m -> {
    Class c = firstMethodArgumentType(m);
    ret isSubclassOf(c, type) ? c : null;
  });
}