public String format(Date then)
   {
      if (then == null)
         then = now();

      Duration d = approximateDuration(then);
      return format(d);
   }
@Test
   public void testRightNowWithReference() throws Exception
   {
      Date now = new Date();
      Date ref = new Date();
      PrettyTime t = new PrettyTime(ref);
      String formatted = t.format(now);
      Assert.assertEquals("moments from now", formatted);
   }