getPlayerCount(appid, callback) {
		return StdLib.Promises.timeoutCallbackPromise(10000, ['playerCount'], callback, (resolve, reject) => {
			this._send(EMsg.ClientGetNumberOfCurrentPlayersDP, {appid}, (body) => {
				let err = Helpers.eresultError(body.eresult);
				if (err) {
					reject(err);
				} else {
					resolve({playerCount: body.player_count});
				}
			});
		});
	}
Get count of people playing a Steam app. Use appid 0 to get number of people connected to Steam.
@param {int} appid
@param {function} [callback]
@returns {Promise<{playerCount: number}>}