docs: public static String formatRuntime(long runtime) {
  
          long seconds = (runtime / SECONDS) % 60;
          long minutes = (runtime / MINUTES) % 60;
          long hours = (runtime / HOURS) % 24;
          long days = runtime / DAYS;
          StringBuffer strBuf = new StringBuffer();
  
          if (days > 0) {
              if (days < 10) {
                  strBuf.append('0');
              }
              strBuf.append(days);
              strBuf.append(':');
          }
  
          if (hours < 10) {
              strBuf.append('0');
          }
          strBuf.append(hours);
          strBuf.append(':');
  
          if (minutes < 10) {
              strBuf.append('0');
          }
          strBuf.append(minutes);
          strBuf.append(':');
  
          if (seconds < 10) {
              strBuf.append('0');
          }
          strBuf.append(seconds);
  
          return strBuf.toString();
      }