users = []
def menu():
    print "Hello, and welcome to Uplink International. If you already have an\
    account, press 1 to create an account, or if you are already a user,\
    press 2 to log in. Press 0 to exit."
    choice = input('What would you like to do? ')
    print ""
    return choice
choice = menu()
if choice == 0:
    print "Goodbye."
    exit
elif choice == 1:
    print "Please enter your desired username and password (case sensitive)."
    print " "
    username = raw_input('Username: ')
    password = raw_input('Password: ')
    users.append([username, password])
elif choice == 2:
    username = raw_input('Username: ')
    password = raw_input('Password: ')
    if [username, password]