public static <T, R> Function<T, R> toUncheckedFunction(FunctionRaisingIOE<T, R> fun) {
    return fun::unchecked;
  }
@Test
  public void testUncheckedFunction() throws Throwable {
    // java function which should raise a FileNotFoundException
    // wrapped into an unchecked exeption
    final Function<String, Object> fn =
        toUncheckedFunction((String a) -> {
          throw new FileNotFoundException(a);
        });
    intercept(UncheckedIOException.class, "missing", () ->
        fn.apply("missing"));
  }