Fix code example
Fix code example

pfnet/chainer,okuta/chainer,tkerola/chainer,keisuke-umezawa/chainer,okuta/chainer,okuta/chainer,keisuke-umezawa/chainer,wkentaro/chainer,hvy/chainer,okuta/chainer,keisuke-umezawa/chainer,chainer/chainer,wkentaro/chainer,hvy/chainer,wkentaro/chainer,hvy/chainer,hvy/chainer,niboshi/chainer,niboshi/chainer,chainer/chainer,niboshi/chainer,chainer/chainer,niboshi/chainer,wkentaro/chainer,chainer/chainer,keisuke-umezawa/chainer