Create an application to compute retirement account balances.
A User will enter the annual savings. Annual savings cannot be blank and must be a positive number. Use a loop to prompt the user to enter annual savings until they get it right.
A user will enter the year that the user will start saving. Start year must be a year between 2015 and 2100 (inclusive). Use a loop to prompt the user to enter the start year until they get it right.