fmap2:: Monad m => (a -> b) -> m a -> m b
fmap2 f xs = do
    x <- xs
    return (f x)

(*>.) :: Monad m => m a -> m b -> m b
xs *>. ys = xs >> ys

liftA2_:: Monad m => (a -> b -> c) -> m a -> m b -> m c
liftA2_ f xs ys = do
    x <- xs
    y <- ys
    return (f x y)