def main(): context = Context(OperationAdd()) print("10 + 5 = " + str(context.executeStrategy(10,5))) context = Context(OperationSubstract()) print("10 - 5 = " + str(context.executeStrategy(10,5))) context = Context(OperationMultiply()) print("10 * 5 = " + str(context.executeStrategy(10,5)))