Kinda late but I want to point out these snippets have different behaviors: if A and B: .. elif B: .. vs if A and B: ..

Kinda late but I want to point out these snippets have different behaviors: if A and B: .. elif B: .. vs if A and B: .. elif A and not B: .. I prefer flattening because enumeration makes it obvious what's different between the branches despite the code duplication. For example, three boolean conditions has 2^3 = 8 possible combinations. When nested this complexity is hidden but obviously apparent as a code smell when flattened. It also echoes Python's ethos that flat is better than nested.