Flavor_symmetries

How should we at best implement flavor symmetry in the code?

Question: Concerning OP_T and OP_V

1. should we provide just minimal changes to programs that are blind to flavor symmetry?
   Upshot: offers more possibilities for debugging.
2. should we design the program with flavor symmetry in mind? Upshot: has no redundancies.
3. General structure --> will follow from 1) and 2).

Please all think about that.