hailstone: This method takes an int n as input and returns its hailstone sequence as a list of integers. The hailstone sequence is defined by the following procedure: pick a positive integer n as the start. If n is even, divide n by $2.$ If n is odd, multiply n by $3$ and add $1.$ Continue this process until n is $1.$

You should compute this using recursion with the provided helper method hailstoneHelper.