Prevent unused variable error
Prevent unused variable error

chainer/chainer,okuta/chainer,hvy/chainer,pfnet/chainer,niboshi/chainer,hvy/chainer,hvy/chainer,okuta/chainer,okuta/chainer,wkentaro/chainer,chainer/chainer,niboshi/chainer,wkentaro/chainer,chainer/chainer,wkentaro/chainer,wkentaro/chainer,niboshi/chainer,okuta/chainer,hvy/chainer,chainer/chainer,niboshi/chainer