def __init__(self):
        """
        Database stores every info.

        version int
        # if value in file is unequal to value defined in this class.
        # An database update will be applied.
        user dict:
            username str
            key str
        collections list:
            collection_info(dict):
                collection_name str
                collection_type str
                collection_describe str
                collection_songs list:
                    song_id(int)
        songs dict:
            song_id(int) dict:
                song_id int
                artist str
                song_name str
                mp3_url str
                album_name str
                album_id str
                quality str
                lyric str
                tlyric str
        player_info dict:
            player_list list[dict]
            playing_order list[int]
            playing_mode int
            playing_offset int


        :return:
        """
        if hasattr(self, "_init"):
            return
        self._init = True

        self.database = {
            "user": {"username": "", "password": "", "user_id": "", "nickname": ""},
            "collections": [],
            "songs": {},
            "player_info": {
                "player_list": [],
                "player_list_type": "",
                "player_list_title": "",
                "playing_order": [],
                "playing_mode": 0,
                "idx": 0,
                "ridx": 0,
                "playing_volume": 60,
            },
        }
        self.storage_path = Constant.storage_path
        self.cookie_path = Constant.cookie_path

        Database stores every info.

        version int
        # if value in file is unequal to value defined in this class.
        # An database update will be applied.
        user dict:
            username str
            key str
        collections list:
            collection_info(dict):
                collection_name str
                collection_type str
                collection_describe str
                collection_songs list:
                    song_id(int)
        songs dict:
            song_id(int) dict:
                song_id int
                artist str
                song_name str
                mp3_url str
                album_name str
                album_id str
                quality str
                lyric str
                tlyric str
        player_info dict:
            player_list list[dict]
            playing_order list[int]
            playing_mode int
            playing_offset int


        :return:
        
NEMbox/storage.py