Write a method that recursively computes the "digit sum" of the given number, by following these rules: #1: The digit sum is computed recursively until a single-digit answer is obtained. #2: The digit sum is found by adding all the digits in the number, except odd digits are "promoted" to the next even digit. For example, the sum of the digits of 134 would be 2+4+4=10 (because the 1 gets promoted to a 2 and the 3 gets promoted to a 4). However, this is not a single-digit answer, so the process is repeated with 10. The sum of those digits is 2 (because the 1 gets promoted to a 2, and 2+0=2). This IS a single digit, so that value, 2, is the result. Look at the test data for further examples. Your solution is allowed to use one loop, but at least part of your solution must be done recursively.