fixed module level import function_node
fixed module level import function_node

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