Update Bag.php
Update Bag.php

fix __toString method
zhaojianhui129/wechat,xinen8721/wechat,hexing-w/wechat,TheNorthMemory/wechat,oamzn/wechat,tenstone/wechat,hgonlywj/wechat,qitianchan/wechat-1,internet-dev/wechat,CoolCloud/wechat-1,TheNorthMemory/wechat,partychen/wechat,fatihwk/wechat,heivin/wechat,kyletiao/wechat,imjerrybao/wechat-1,YeFatBoy/wechat,liwanwei/wechat,shanyimin/wechat,wochicaomei/wechat,flybird119/wechat-1,let5sne/wechat,huyanping/wechat,bspiritxp/wechat,mojiajuzi/wechat,gududefengzhong/wechat-1,mickelfeng/wechat-1