@Test
public void testIfThen() {

  assertEquals(some("hallo"), some("hello").map(ifThen("hello", "hallo")));
  assertEquals(some(-1), some("none").map(ifThen("none", "-1")).bind(Strings.toInt).orError(new RuntimeException()));
  assertEquals(some(300), some("300").map(ifThen("none", "-1")).bind(Strings.toInt).orError(new RuntimeException()));
}