Solve the problems related to these modules:
Module 1: Implement the buttons' function to call each method according to its name.
Module 2: Implement the Login Function
Module 3: Implement fast food GUI and its functions
Module 4: Receipt Panel
Module 5: Required Modifier
Module 6: Non-required Modifier
Module 7: Back Office
Module 8: Other Button - Split, Discount
Module 9: Credit Card Button
Module 11: Gift Card Button & Cash Button