code: public static String computeTimeAgoString(long ts, String suffix) {
          long now = System.currentTimeMillis();
  
          checkArgument(ts <= now, "Cannot handle timestamp in the future" +
                  ", now: " + now + "/" + new Date(now) + 
                  ", ts: " + ts + "/" + new Date(ts));
  
          long diff = now - ts;
          return timeToReadable(diff, suffix);
      }
docs: Takes the time in milliseconds since the epoch and
  converts it into a string of "x days/hours/minutes/seconds"
  compared to the current time.
  
  @param ts The timestamp in milliseconds since the epoch
  @param suffix Some text that is appended only if there is a time-difference, i.e.
  it is not appended when the time is now.
  
  @return A readable string with a short description of how long ago the ts was.