Tong Li

I think this may be a version issue. I solved it by adding some parameters which not exisit in Pytorch 0.3 or lower. Perhaps [this](https://discuss.pytorch.org/t/batchnorm2d-object-has-no-attribute-track-running-stats/17525/15) will help you. Or you...

@xinix909 Hello, you said "Flow wrap method is wrong I think." Did you mean that the `warp(x,flo)` function in `utilities.py`? I think the function may be used to calculate img1...