Write a function mode_digit that takes an integer number n and returns the digit that appears most frequently in that number. The given number may be positive or negative, but the most frequent digit returned should always be non-negative. If there is a tie for the most frequent digit, the digit with the greatest value should be returned. To receive full credit, your solution must not create strings in any way to solve any part of the problem. You must also not use any nested loops or recursion (if you don't know what that is, you aren't using it). You must not have an if/elif/else branch for each digit. You are allowed to use extra storage to solve this problem. Here are some example calls