X69: fix34

Return an array that contains exactly the same numbers as the given array but re-arranged so that every 3 is immediately followed by a 4. Do not move the 3s, but every other number may move. The array contains the same number of 3s and 4s, every 3 has a number after it that is not a 3 or 4, and a 3 appears in the array before any 4.