old_contents: """
  Main world controller.
  """
  
  from appstate import AppState
  import pygame
  import events
  
  class Controller(events.EventListener):
      """
      Controller class.
      """
  
      def __init__(self):
          pass
  
      def _quit(self):
          """ 
          Gracefully quit the simulator.
          """
  
          quitEvent = events.QuitEvent()
          AppState.get_state().get_event_manager().post_event(quitEvent)
  
      def process_input(self):
          """
          Process user input.
          """
  
          for event in pygame.event.get():
              if event.type == pygame.QUIT: 
                  self._quit()
                  return
              elif event.type == pygame.KEYDOWN:
                  if event.key == pygame.K_ESCAPE:
                      self._quit()
                      return
  
                  pygame.M
  
      def notify(self, event):
          if isinstance(event, events.TickEvent):
              self.process_input()
new_contents: """
  Main world controller.
  """
  
  from appstate import AppState
  import pygame
  import events
  
  class Controller(events.EventListener):
      """
      Controller class.
      """
  
      def __init__(self):
          pass
  
      def _quit(self):
          """ 
          Gracefully quit the simulator.
          """
  
          quitEvent = events.QuitEvent()
          AppState.get_state().get_event_manager().post_event(quitEvent)
  
      def process_input(self):
          """
          Process user input.
          """
  
          for event in pygame.event.get():
              if event.type == pygame.QUIT: 
                  self._quit()
                  return
              elif event.type == pygame.KEYDOWN:
                  if event.key == pygame.K_ESCAPE:
                      self._quit()
                      return
  
      def notify(self, event):
          if isinstance(event, events.TickEvent):
              self.process_input()
subject: Fix bug crashing the experiment on a non-recognized keypress.