Flake8: fix import order.
Flake8: fix import order.

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