Fix: adding import nececeary for using attention layers as bottlenecks

[rasmuspjohansson]

Adding the following import
from fastai.layers import _get_norm
in order for the following code to be able to run

def BatchNormZero(nf, ndim=2, **kwargs):\n",
" "BatchNorm layer with nf features and ndim initialized depending on norm_type. Weights initialized to zero."\n",
" return _get_norm('BatchNorm', nf, ndim, zero=True, **kwargs)\n",

After this fix it becomes possible to train a timm model based unet with attention or double_attention as bottleneck

[review-notebook-app]

Check out this pull request on 

See visual diffs & provide feedback on Jupyter Notebooks.

---

Powered by ReviewNB

[muellerzr]

Thanks!