improve Variable guide
improve Variable guide

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