Warn if to_device is skipped
Warn if to_device is skipped

chainer/chainer,chainer/chainer,hvy/chainer,chainer/chainer,wkentaro/chainer,wkentaro/chainer,hvy/chainer,pfnet/chainer,niboshi/chainer,wkentaro/chainer,chainer/chainer,niboshi/chainer,hvy/chainer,niboshi/chainer,hvy/chainer,niboshi/chainer,wkentaro/chainer