Write a recursive Racket function "update-if" that takes two functions, f and g, and a list xs as parameters and evaluates to a list. f will be a function that takes one parameter and checks if the input if even... and then returns true or false. g will be a function that takes one parameter and evaluates to some output (for example if you pass in add1 then g(2) should be 3.. if you passed in the function sub1 then g(2) should be 1. The result of update-if should be a list of items such that if x is in xs and (f x) is true, then (g x) is in the list. The output list's elements should keep the input list's items in the same relative order.

For example (update-if even? add1 '(1 2 3 4)) should evaluate to '(3 5) because 2 and 4 make even? true and add1 turns 2 and 4 into 3 and 5.