MAINT fix some PEP8 errors
MAINT fix some PEP8 errors

raybuhr/pyfolio,chayapan/pyfolio,YihaoLu/pyfolio,yanheven/pyfolio,YihaoLu/pyfolio,femtotrader/pyfolio,ChinaQuants/pyfolio,r0k3/pyfolio,r0k3/pyfolio,femtotrader/pyfolio,sketchytechky/pyfolio,ChinaQuants/pyfolio,dursk/pyfolio,quantopian/pyfolio,sketchytechky/pyfolio,dursk/pyfolio,quantopian/pyfolio,yanheven/pyfolio,raybuhr/pyfolio