imagenet_example cannot run
🐛 Bug

imagenet_example cannot be executed
To Reproduce
Steps to reproduce the behavior:

Download imagenet
cd pl_examples/full_examples/imagenet
python imagenet_example.py --data-path imagenet_path


Error:
Traceback (most recent call last):
  File "imagenet_example.py", line 248, in <module>
    main(get_args())
  File "imagenet_example.py", line 229, in main
    model = ImageNetLightningModel(hparams)
TypeError: Can't instantiate abstract class ImageNetLightningModel with abstract methods forward

Expected behavior

The example should run.
Environment
PyTorch version: 1.3.1
Is debug build: No
CUDA used to build PyTorch: 10.1.243
OS: Ubuntu 18.04.3 LTS
GCC version: (Ubuntu 7.4.0-1ubuntu1~18.04.1) 7.4.0
CMake version: Could not collect
Python version: 3.7
Is CUDA available: Yes
CUDA runtime version: Could not collect
GPU models and configuration: GPU 0: GeForce RTX 2080 Ti
Nvidia driver version: 440.44
cuDNN version: Could not collect
Versions of relevant libraries:
[pip3] numpy==1.18.1
[pip3] pytorch-lightning==0.6.0
[pip3] torch==1.3.1
[pip3] torchvision==0.4.2
[conda] blas                      1.0                         mkl
[conda] mkl                       2019.4                      243
[conda] mkl-service               2.3.0            py37he904b0f_0
[conda] mkl_fft                   1.0.14           py37ha843d7b_0
[conda] mkl_random                1.1.0            py37hd6b4f25_0
Additional context

I suspect that there was breaking changes in the API and that the example is obsolete as the method forward is now expected.