Problem $1$

;;

;; Using the data definition for ListOfInteger, design a function called

;; even$-$only that consumes a list of integers and produces a list that

;; only contains the even integers. Note that there is a primitive named

;; even? that you will find helpful!

$($@problem $1)$

$($@htdd ListOfInteger$)$

;; ListOfInteger is one of:

;; $-$ empty

;; $-($cons Integer ListOfInteger$)$

;; interp. a list of integers