what variables used in this following python code - # Define the filename Accounts_File = "accounts.txt" #Register a new username and password def register_account(): print(" --- Register New Account ---") username = input("Enter a new username: ") .strip() password = input("Enter a new password: ") .strip() #check if the username already exists if sys.path.exists(Accounts_File): with open(Accounts_File, 'r') as file: for line in file: existing_username = line.strip().split(',') [0] if username == existing_username: print("Username already exists. Please try a different username.") return #Write the new account to the file with open(Accounts_File, 'a') as file: file.write(f"{username} , {password} ") print("Account successfully registered") #Check username and password (Login) def login(): print(" --- Login ---") username = input("Enter your username: ") .strip() password = input("Enter your password: "). strip() success = False if sys.path.exists(Accounts_File): with open(Accounts_File, 'r') as file: for line in file: stored_username, stored_password = line.strip() .split(',') if username == stored_username and password == stored_password: success = True break