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 dictionary.
- Updates the log_in dictionary, setting the value to False.
- 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
