You have been asked to write a username validation program for a small website. The website has specific rules on what constitutes a valid username, including: All usernames must be between 8 and 15 characters long
Usernames can only contain alphabetic (a-z and A-Z) and numeric characters (0-9) - no special characters or spaces are allowed.
The first and last characters in a username cannot be a digit
Usernames must contain at least one uppercase character
Usernames must contain at least one lowercase character
Usernames must contain at least one numeric character

Write a program that asks the user to enter in a username and then examines that username to make sure it complies with the rules above.