from Singleton import Singleton from PricingRule import PricingRule from Checkout import Checkout if __name__ == '__main__': singleton = Singleton.get_instance() co = Checkout(PricingRule()) co.scan(singleton.productManager.get_product('mbp')) co.scan(singleton.productManager.get_product('vga')) co.scan(singleton.productManager.get_product('vga')) print(co.total())