Add _product, which should be implemented as testing.parametrized.product
Add _product, which should be implemented as testing.parametrized.product

benob/chainer,keisuke-umezawa/chainer,ronekko/chainer,tkerola/chainer,sinhrks/chainer,truongdq/chainer,okuta/chainer,keisuke-umezawa/chainer,delta2323/chainer,chainer/chainer,okuta/chainer,benob/chainer,cupy/cupy,muupan/chainer,anaruse/chainer,rezoo/chainer,wkentaro/chainer,chainer/chainer,wkentaro/chainer,niboshi/chainer,ysekky/chainer,ktnyt/chainer,kikusu/chainer,niboshi/chainer,okuta/chainer,chainer/chainer,wkentaro/chainer,cupy/cupy,keisuke-umezawa/chainer,kikusu/chainer,jnishi/chainer,ktnyt/chainer,jnishi/chainer,muupan/chainer,aonotas/chainer,hvy/chainer,kashif/chainer,hvy/chainer,niboshi/chainer,ktnyt/chainer,pfnet/chainer,t-abe/chainer,truongdq/chainer,hvy/chainer,niboshi/chainer,AlpacaDB/chainer,okuta/chainer,jnishi/chainer,kiyukuta/chainer,cupy/cupy,sinhrks/chainer,wkentaro/chainer,chainer/chainer,keisuke-umezawa/chainer,t-abe/chainer,ktnyt/chainer,AlpacaDB/chainer,cemoody/chainer,cupy/cupy,hvy/chainer,jnishi/chainer