In this assignment, you will implement an online banking system. Users can sign-up with the system, log in to the system, change their password, and delete their account. They can also update their bank account balance and transfer money to another users bank account.

Youll implement functions related to File I/O and dictionaries. The first two functions require you to import files and create dictionaries. User information will be imported from the users.txt file and account information will be imported from the bank.txt file. Take a look at the content in the different files. The remaining functions require you to use or modify the two dictionaries created from the files.

Each function has been defined for you, but without the code. See the docstring in each function for instructions on what the function is supposed to do and how to write the code. It should be clear enough. In some cases, we have provided hints to help you get started.

def signup(user_accounts, log_in, username, password): ''' This function allows users to sign up. If both username and password meet the requirements, updates the username and the corresponding password in the user_accounts, and returns True. If the username and password fail to meet any one of the following requirements, returns False. - The username already exists in the user_accounts. - The password must be at least 8 characters. - The password must contain at least one lowercase character. - The password must contain at least one uppercase character. - The password must contain at least one number. - The username & password cannot be the same. For example: - Calling signup(user_accounts, log_in, "Brandon", "123abcABCD") will return False - Calling signup(user_accounts, log_in, "BrandonK", "123ABCD") will return False - Calling signup(user_accounts, log_in, "BrandonK","abcdABCD") will return False - Calling signup(user_accounts, log_in, "BrandonK", "123aABCD") will return True. Then calling signup(user_accounts, log_in, "BrandonK", "123aABCD") again will return False. Hint: Think about defining and using a separate valid(password) function that checks the validity of a given password. This will also come in handy when writing the change_password() function. ''' # your code here

def import_and_create_accounts(filename): ''' This function is used to create an user accounts dictionary and another login dictionary. The given argument is the filename to load. Every line in the file will look like username - password

If the username and password fulfills the requirement, add the username and password into the user accounts dictionary. To make sure that the password fulfills these requirements, be sure to use the signup function that you wrote above. For the login dictionary, the key is the username, and its value indicates whether the user is logged in, or not. Initially, all users are not logged in.

Finally, return the dictionaries.

Note: All of the users in the bank file are in the user account file.

def login(user_accounts, log_in, username, password): ''' This function allows users to log in with their username and password. The users_accounts stores the usernames and passwords.

If the username does not exist or the password is incorrect, return False. Otherwise, return True.

For example: - Calling login(user_accounts, "Brandon", "123abcAB") will return False - Calling login(user_accounts, "Brandon", "brandon123ABC") will return True Note: If a user is already logged in, this should return False - a user cannot log in a second time once logged in