public String formatDuration(Date then)
   {
      Duration duration = approximateDuration(then);
      return formatDuration(duration);
   }
@Test
   public void testFormatDuration() throws Exception
   {
      long tenMinMillis = java.util.concurrent.TimeUnit.MINUTES.toMillis(10);
      Date tenMinAgo = new Date(System.currentTimeMillis() - tenMinMillis);
      PrettyTime t = new PrettyTime();
      String result = t.formatDuration(tenMinAgo);
      Assert.assertEquals("10 minutes", result);

      result = t.formatDuration(now.minusMinutes(10));
      Assert.assertEquals("10 minutes", result);
   }