Can someone help me with this and explain how they came up with solution. Must be in python language. Thanks!

def plus_one(digits): This is to review loops and if statements Given a non-empty array of digits representing a non-negative integer, plus one to the integer. You can do this in-place! The digits are stored such that the most significant digit is at the head of the list, and each element in the array contain a single digit. You may assume the integer does not contain any leading zero, except the number 0 itself. Example 1: Input: digits = [1, 2, 3] Output: digits = [1, 2, 4] Explanation: The array represents the integer 123. Example 2: Input: digits = [1, 0, 9, 9] Output: digits = [1, 1, 0, 0] . . return digits