// separate above
    assertEquals(Range.closed(4, 12), range.span(Range.closed(10, 12)));
    assertEquals(Range.atLeast(4), range.span(Range.atLeast(10)));
  }

  public void testApply() {
    Predicate<Integer> predicate = Range.closed(2, 3);
    assertFalse(predicate.apply(1));
    assertTrue(predicate.apply(2));
    assertTrue(predicate.apply(3));
    assertFalse(predicate.apply(4));
  }