This example requires pytorch.
pytorch install package should be chosen based on python version and cuda version.

Here is an example of the environment python==3.5 and cuda == 8.0, then using the following commands to install pytorch:
python3 -m pip install http://download.pytorch.org/whl/cu80/torch-0.4.1-cp35-cp35m-linux_x86_64.whl 
python3 -m pip install torchvision