IT by maximum value n.
-}
new :: Monoid a => Int -> BIT a
new n = BIT n (V.replicate (n+1) mempty) -- we can use f
new :: Monoid a => Int -> BIT a
new n = BIT n (V.replicate (n+1) mempty)
new n = BIT n (V.replicate (n+1) mempty)