text: from customer import Customer
  from soda_machine import SodaMachine
  import user_interface
  
  class Simulation:
      def __init__(self):
          pass
  
      def run_simulation(self):
          """The central method called in main.py."""
          customer = Customer()
          soda_machine = SodaMachine()
          will_proceed = False
          while will_proceed:
              user_option = user_interface.simulation_main_menu()
              if user_option == "1":
                  soda_machine.begin_transaction(customer)
              elif user_option == "2":
                  customer.check_coins_in_wallet()
              elif user_option == "3":
                  customer.check_backpack()
              else:
                  will_proceed = False
  