public static function enable(interfaces\handlers\Error $error = null, interfaces\handlers\Exception $exception = null, $threshold = null) : bool
    {
        // Only enable the Handlers once. See the class description for more on this.
        if (static::$enabled) {
            return false;
        }

        // Register the Handlers.
        static::$errorHandler     = handlers\Error::register($error, $threshold);
        static::$exceptionHandler = handlers\Exception::register($exception);

        return static::$enabled = true;
    }