getKey(datetime, type) {
        switch (type) {
            case "day":
                return this.getDailyKey(datetime);
            case "hour":
                return this.getHourlyKey(datetime);
            case "minute":
                return this.getMinutelyKey(datetime);
            default:
                throw new Error("Invalid type");
        }
    }
Convert timestamp to key
@param {dayjs.Dayjs} datetime Datetime
@param {"day" | "hour" | "minute"} type the type of data which is expected to be returned
@returns {number} Timestamp
@throws {Error} If the type is invalid