a) Complete the following function to return number of occurences of the first parameter in the second parameter list. occurs 1 [1,2,3,1,2] will return 2 since 1 has 2 occurrences in the list. occurs 3 [1,2,3,1,2] will return 1 and occurs 4 [1,2,3,1,2] will return 0. occurs [] = 0 occurs a (x:xs) = let rest occurs a xs in if a==x then b) Complete the following function to return number of occurences of the first parameter in the nodes of the second parameter tree. The definition of tree is given below. In the sample tree t the calls return the corresponding values: occurst 1 t6 occurst 2 t2 occurst 3 t1 occurst 4 t-0 else data Tree a = Node (a, Tree a, Tree a) | Empty deriving Show occurst Empty = 0 - occurst a (Node (x, left, right)) t = Node (3, Node Node = (2, Node (1, Empty, Empty), Node (1, Empty, Empty)), (1, Node (2, Node (1, Empty, Empty), Node (1, Empty, Empty)), Node (1, Empty, Empty) ))