code: def autodoc_event_handlers(stream=sys.stdout):
      
      lines = []
      for cls in all_subclasses(EventHandler):
          if cls in _ABC_EVHANDLER_CLASSES: continue
          event_class = cls.event_class
          lines.extend(cls.cls2str().split("\n"))
  
          # Here we enforce the abstract protocol of the class
          # The unit test in tests_events will detect the problem.
          if not hasattr(cls, "can_change_physics"):
              raise RuntimeError("%s: can_change_physics must be defined" % cls)
  
      stream.write("\n".join(lines) + "\n")
docs: Print to the given string, the documentation for the events
      and the associated handlers.