validating user input and loops

[sparkz_alot]

In line 11 of the above code, you define "input_string" as an empty string, where do you update it (prior to calling "is_valid_integer")?  What other variable might you use as an argument when calling that function?

If you have not covered lists, or you are confused by what you see, do not use it in your code. What will you do when your teacher asks you to explain to the class what you did and why you did it?