3. Write a function repeat_map : ('a -> 'a) -> 'a list -> 'a list such that repeat_map f xs applies f once to the first element of xs, twice to the second, three times to the third, and so on. 3. Write a function repeat_map : ('a -> 'a) -> 'a list -> 'a list such that repeat_map f xs applies f once to the first element of xs, twice to the second, three times to the third, and so on