check whether list[0] exists or return null
check whether list[0] exists or return null

bunnyblue/tchannel,hustxiaoc/tchannel,Zirpon/tchannel,hustxiaoc/tchannel,davewhat/tchannel,i/tchannel,i/tchannel,vanloswang/tchannel,Zirpon/tchannel,sasa233/tchannel,chenwenbin928/tchannel,davewhat/tchannel,vanloswang/tchannel,savaki/tchannel,chenwenbin928/tchannel,hustxiaoc/tchannel,RyanTech/tchannel,bunnyblue/tchannel,chenwenbin928/tchannel,benfleis/tchannel,bunnyblue/tchannel,benfleis/tchannel,savaki/tchannel,RyanTech/tchannel,Zirpon/tchannel,RyanTech/tchannel,vanloswang/tchannel,savaki/tchannel,sasa233/tchannel,sasa233/tchannel,i/tchannel,benfleis/tchannel