protected function _evaluateCondition($condition, Event $event)
    {
        if (!isset($this->_options[$condition])) {
            return $condition !== 'unless';
        }
        if (!is_callable($this->_options[$condition])) {
            throw new RuntimeException(self::class . ' the `' . $condition . '` condition is not a callable!');
        }

        return $this->_options[$condition]($event);
    }