Add an abstract Flow class to document the expected interface of a normalizing flow

[andrrizzi]

We could then use this class to document methods like tfep.app.TFEPMapBase.configure_flow().

[ayushkanyal]

Hey @andrrizzi , I am new to open-source and would love to contribute to this project. Please let me know if you need help with this project, and how I can help you with the same.

[andrrizzi]

Thanks a lot for your offer, @ayushkanyal! I'm in the middle of a big refactoring and adding more documentation to the repo, but if you want to start this might be a good start.

It's about creating a Python abstract class called tfep.nn.flows.base.FlowBase that includes and document the necessary methods to define a normalizing flow (i.e., forward() and inverse()). Feel free to fork the project and open a PR if you have time. Apologies for the lack of dev documentation at the moment, but you can take hints from the other classes in the tfep.nn.flows package.

[ayushkanyal]

Hey @andrrizzi, thanks for the headsup. I've gone through your comment and the repository, I feel I know very little about abstract classes in python and free energy perturbation. Thank you so much for taking the time to explain everything though. I hope I can contribute when my knowledge/skills are there to contribute. Hope this helped anyone looking to contribute. Sorry about taking your time.