fix core.pyx:  reflects comments
fix core.pyx:  reflects comments

hvy/chainer,delta2323/chainer,wkentaro/chainer,jnishi/chainer,ktnyt/chainer,okuta/chainer,wkentaro/chainer,cupy/cupy,kashif/chainer,hvy/chainer,niboshi/chainer,okuta/chainer,hvy/chainer,ktnyt/chainer,tkerola/chainer,keisuke-umezawa/chainer,hvy/chainer,ktnyt/chainer,ktnyt/chainer,chainer/chainer,okuta/chainer,okuta/chainer,wkentaro/chainer,ysekky/chainer,jnishi/chainer,ronekko/chainer,wkentaro/chainer,pfnet/chainer,aonotas/chainer,keisuke-umezawa/chainer,keisuke-umezawa/chainer,niboshi/chainer,kiyukuta/chainer,keisuke-umezawa/chainer,niboshi/chainer,rezoo/chainer,jnishi/chainer,chainer/chainer,cupy/cupy,niboshi/chainer,cupy/cupy,cupy/cupy,anaruse/chainer,chainer/chainer,jnishi/chainer,chainer/chainer