Remove unused import line
Remove unused import line

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