fix flake8
fix flake8

kiyukuta/chainer,chainer/chainer,keisuke-umezawa/chainer,anaruse/chainer,cupy/cupy,cupy/cupy,ktnyt/chainer,wkentaro/chainer,chainer/chainer,wkentaro/chainer,keisuke-umezawa/chainer,ronekko/chainer,niboshi/chainer,wkentaro/chainer,jnishi/chainer,jnishi/chainer,niboshi/chainer,tkerola/chainer,ktnyt/chainer,ysekky/chainer,kashif/chainer,pfnet/chainer,okuta/chainer,aonotas/chainer,rezoo/chainer,niboshi/chainer,hvy/chainer,jnishi/chainer,cupy/cupy,hvy/chainer,hvy/chainer,okuta/chainer,chainer/chainer,ktnyt/chainer,chainer/chainer,jnishi/chainer,hvy/chainer,okuta/chainer,niboshi/chainer,delta2323/chainer,keisuke-umezawa/chainer,keisuke-umezawa/chainer,okuta/chainer,cupy/cupy,wkentaro/chainer,ktnyt/chainer