deriveModality a                  = [(0 + offset) `mod` 12, (2 + offset) `mod` 12, (3 + offset) `mod` 12, (5 + offset) `mod` 12, (7 + offset) `mod` 12, (8 + offset) `mod` 12, (10 + offset) `mod` 12] where offset = deriveOffset a
deriveModality a                  = [(0 + offset) `mod` 12, (2 + offset) `mod` 12, (3 + offset) `mod` 12, (5 + offset) `mod` 12, (7 + offset) `mod` 12, (8 + offset) `mod` 12, (10 + offset) `mod` 12] where offset = deriveOffset a
deriveModality a                  = [(0 + offset) `mod` 12, (2 + offset) `mod` 12, (3 + offset) `mod` 12, (5 + offset) `mod` 12, (7 + offset) `mod` 12, (8 + offset) `mod` 12, (10 + offset) `mod` 12] where offset = deriveOffset a