Removes unused import.
Removes unused import.

umuzungu/zipline,AlirezaShahabi/zipline,cmorgan/zipline,euri10/zipline,MonoCloud/zipline,enigmampc/catalyst,keir-rex/zipline,dkushner/zipline,magne-max/zipline-ja,florentchandelier/zipline,magne-max/zipline-ja,bartosh/zipline,aajtodd/zipline,zhoulingjun/zipline,florentchandelier/zipline,chrjxj/zipline,dhruvparamhans/zipline,sketchytechky/zipline,quantopian/zipline,michaeljohnbennett/zipline,erikness/AlephOne,StratsOn/zipline,DVegaCapital/zipline,davidastephens/zipline,otmaneJai/Zipline,wilsonkichoi/zipline,michaeljohnbennett/zipline,nborggren/zipline,euri10/zipline,wubr2000/zipline,alphaBenj/zipline,YuepengGuo/zipline,keir-rex/zipline,sketchytechky/zipline,iamkingmaker/zipline,aajtodd/zipline,mattcaldwell/zipline,wilsonkichoi/zipline,dmitriz/zipline,stkubr/zipline,otmaneJai/Zipline,CDSFinance/zipline,bartosh/zipline,joequant/zipline,AlirezaShahabi/zipline,zhoulingjun/zipline,dhruvparamhans/zipline,CarterBain/AlephNull,DVegaCapital/zipline,erikness/AlephOne,mattcaldwell/zipline,dmitriz/zipline,morrisonwudi/zipline,davidastephens/zipline,ronalcc/zipline,umuzungu/zipline,jordancheah/zipline,CDSFinance/zipline,semio/zipline,YuepengGuo/zipline,grundgruen/zipline,semio/zipline,humdings/zipline,Scapogo/zipline,humdings/zipline,gwulfs/zipline,alphaBenj/zipline,kmather73/zipline,StratsOn/zipline,wubr2000/zipline,quantopian/zipline,ChinaQuants/zipline,jimgoo/zipline-fork,nborggren/zipline,stkubr/zipline,jordancheah/zipline,Scapogo/zipline,cmorgan/zipline,chrjxj/zipline,ChinaQuants/zipline,morrisonwudi/zipline,ronalcc/zipline,jimgoo/zipline-fork,CarterBain/AlephNull,enigmampc/catalyst,iamkingmaker/zipline,MonoCloud/zipline,dkushner/zipline,grundgruen/zipline,joequant/zipline,gwulfs/zipline,kmather73/zipline