Common Interview Question that comes up where you are asked to sort integers in an array based on the frequency. If there are ties, then you sort the integers in their natural order. For example: if given the array: [5, 2, 3, 1, 5, 5, 7, 10, 7]. This function should return: [5, 5, 5, 7, 7, 1, 2, 3, 10].