Implement the Luhn Algorithm

The Luhn algorithm, also known as the "modulus 10" or "mod 10" algorithm, is a simple checksum formula used to validate a variety of identification numbers, like credit card numbers. These are the steps to validate a number using the Luhn algorithm: - Starting from the right, and excluding the rightmost digit (the check digit), double the value of every other digit. - If the result of doubling a digit is greater than `9`, sum the digits to get a single digit. Alternatively, you can subtract `9` from the result. - Take the sum of all the digits including the check digit. - If the sum of all the digits is a multiple of `10`, then the number is valid; else it is not valid. For example, consider the number `453914881`. The steps to validate it using the Luhn algorithm are: ```md Account number 4 5 3 9 1 4 8 8 1 Double every other 4 10 3 18 1 8 8 16 1 Sum 2-char digits 4 1 3 9 1 8 8 7 1 ``` - Then sum all numbers, `4 + 1 + 3 + 9 + 1 + 8 + 8 + 7 + 1 = 42`. - Since `42` is not a multiple of `10`, the number is invalid. In this lab, you will build a credit card validator using the Luhn algorithm. **Objective:** Fulfill the user stories below and get all the tests to pass to complete the lab. **User Stories:** 1. You should define a function named `verify_card_number` that takes a string of digits (representing a card number) and verifies whether it is valid according to the Luhn algorithm. 2. Within the `verify_card_number` function: - You should handle any dashes or spaces that may be present in the card number passed to it. - Return `VALID!` if the card number is valid; otherwise, return `INVALID!`. When you complete the project, you should see the following messages depending on the input: | Card Number | Message | | ------------------- | -------- | | 453914889 | VALID! | | 4111-1111-1111-1111 | VALID! | | 1234 5678 9012 3456 | INVALID! |