4. Implement function, q4(L, goalX, goalY), that takes a non-empty list, L, of [x,y) pairs, and two goal numbers, and returns tuple (closestXY, XorY) where closestXY is the item from L whose x distance from goal X or whose y distance from goalY is the minimum among all distances, and XorY is 'x' if x distance is minimized and 'y' otherwise. You may assume there is a unique answer. Note: You may not use built-in min or max functions. Examples: q4([[4, 4], [10, 10]], 1, 8) should return ([10,10], 'y'). q4 ([[10, 25], [2, 2], [49, 200]], 50, 8) should return ([49,200], 'x')