public static function add($key, $value) {

		if(null === $value && is_array($key)) {

			foreach($key as $index => $value) {
				static :: $data[$index] = $value;
			}

			return;
		}

		if(true === isset(static :: $data[$key]) && true === is_array(static :: $data[$key])) {

			if(true === is_array($value)) {
				$value = array_merge(static :: $data[$key], $value);	
			}
			else {
				static :: $data[$key][] = $value;
			}
		}

		static :: $data[$key] = $value;
	}