Remove unused import
Remove unused import

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