Given 2 int arrays, a and b, each length 3, return a new array length 2 containing their middle elements. For example: middle_two([1, 2, 3], [4, 5, 6]) → [2, 5] middle_two([7, 8, 9], [10, 11, 12]) → [8, 11] middle_two([4, 5, 6], [8, 9, 10]) → [5, 9]