fix doctest
fix doctest

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