Properimages fails basic import modules

[Exkalamity]

I installed properimages using pip install proper images and then started writing the tutorial in a Jupyter Notebook. However I get this bug when trying to import the module

[BrunoSanchez]

This is due to a change of API of attrs.
I will generate a patch for this. Thanks

[BrunoSanchez]

Please check this has been fixed in #82
Thanks.
If it works I will close this issue.