Remove unused import
Remove unused import

hvy/chainer,t-abe/chainer,sinhrks/chainer,niboshi/chainer,cupy/cupy,chainer/chainer,ktnyt/chainer,delta2323/chainer,ysekky/chainer,chainer/chainer,cupy/cupy,AlpacaDB/chainer,keisuke-umezawa/chainer,okuta/chainer,okuta/chainer,jnishi/chainer,wkentaro/chainer,okuta/chainer,ktnyt/chainer,okuta/chainer,muupan/chainer,keisuke-umezawa/chainer,jnishi/chainer,truongdq/chainer,anaruse/chainer,pfnet/chainer,kiyukuta/chainer,niboshi/chainer,tkerola/chainer,cupy/cupy,wkentaro/chainer,keisuke-umezawa/chainer,muupan/chainer,jnishi/chainer,t-abe/chainer,truongdq/chainer,niboshi/chainer,chainer/chainer,keisuke-umezawa/chainer,hvy/chainer,kikusu/chainer,cupy/cupy,niboshi/chainer,sinhrks/chainer,jnishi/chainer,kikusu/chainer,ronekko/chainer,wkentaro/chainer,hvy/chainer,ktnyt/chainer,hvy/chainer,rezoo/chainer,benob/chainer,AlpacaDB/chainer,kashif/chainer,cemoody/chainer,benob/chainer,chainer/chainer,wkentaro/chainer,ktnyt/chainer,aonotas/chainer