-- | Find the index of a bell. Indices are 1-based, i.e. they are between 1 and
-- @n@, the number of bells.
findBell                 :: Row -> Bell -> Int
findBell (Row bs) b | toInt b > length bs = error "Bell out of range"
                    | otherwise           = (1+) $ length $ takeWhile (/= b) bs
findBell                 :: Row -> Bell -> Int
findBell (Row bs) b | toInt b > length bs = error "Bell out of range"
                    | otherwise           = (1+) $ length $ takeWhile (/= b) bs
findBell (Row bs) b | toInt b > length bs = error "Bell out of range"
                    | otherwise           = (1+) $ length $ takeWhile (/= b) bs