  public static function timer($id = 1, $precision = 4){

    static
      $timers = array();

    // check if this timer was started, and display the elapsed time if so
    if(isset($timers[$id])){
      $elapsed = round(microtime(true) - $timers[$id], $precision);
      unset($timers[$id]);
      return $elapsed;
    }

    // ID doesn't exist, start new timer
    $timers[$id] = microtime(true);
  }