code: public String format(Date then)
     {
        if (then == null)
           then = now();
  
        Duration d = approximateDuration(then);
        return format(d);
     }
docs: Format the given {@link Date} object. If the given {@link Date} is <code>null</code>, the current value of
  {@link System#currentTimeMillis()} will be used instead.
  
  @param then the {@link Date} to be formatted
  @return A formatted string representing {@code then}