testRangeOverlap() {
    assertEquals(RangeOverlap.LEFT, rangeOverlap(1, 2, 3, 4));
    assertEquals(RangeOverlap.LEFT, rangeOverlap(2, 3, 3, 4));
    assertEquals(RangeOverlap.LEFT_IN, rangeOverlap(1, 3, 2, 4));
    assertEquals(RangeOverlap.IN, rangeOverlap(1, 3, 1, 4));
    assertEquals(RangeOverlap.IN, rangeOverlap(2, 3, 1, 4));
    assertEquals(RangeOverlap.IN, rangeOverlap(3, 4, 1, 4));
    assertEquals(RangeOverlap.RIGHT_IN, rangeOverlap(2, 4, 1, 3));
    assertEquals(RangeOverlap.RIGHT, rangeOverlap(2, 3, 1, 2));
    assertEquals(RangeOverlap.RIGHT, rangeOverlap(3, 4, 1, 2));
    assertEquals(RangeOverlap.CONTAINS, rangeOverlap(1, 4, 2, 3));
  }
Test the utility function which tells how two one dimensional ranges
overlap.