fix flake8
fix flake8

hvy/chainer,chainer/chainer,niboshi/chainer,ktnyt/chainer,jnishi/chainer,ronekko/chainer,wkentaro/chainer,okuta/chainer,hvy/chainer,pfnet/chainer,ktnyt/chainer,okuta/chainer,keisuke-umezawa/chainer,keisuke-umezawa/chainer,okuta/chainer,keisuke-umezawa/chainer,niboshi/chainer,aonotas/chainer,jnishi/chainer,anaruse/chainer,tkerola/chainer,chainer/chainer,jnishi/chainer,jnishi/chainer,niboshi/chainer,chainer/chainer,okuta/chainer,wkentaro/chainer,wkentaro/chainer,chainer/chainer,wkentaro/chainer,niboshi/chainer,rezoo/chainer,hvy/chainer,hvy/chainer,ktnyt/chainer,keisuke-umezawa/chainer,ktnyt/chainer