async muteChat(chatId, unmuteDate) {
        unmuteDate = unmuteDate ? Math.floor(unmuteDate.getTime() / 1000) : -1;
        return this._muteUnmuteChat(chatId, 'MUTE', unmuteDate);
    }
Mutes this chat forever, unless a date is specified
@param {string} chatId ID of the chat that will be muted
@param {?Date} unmuteDate Date when the chat will be unmuted, don't provide a value to mute forever
@returns {Promise<{isMuted: boolean, muteExpiration: number}>}