code: def insert(self, identified):
          
  
          if not isinstance(identified, self._class):
              raise self.Error("Passed instance is not of the needed class",
                               self.Error.INVALID_INSTANCE_CLASS, instance=identified)
  
          try:
              if self._objects[identified.key] != identified:
                  raise self.Error("Passes instance's key '%s' is already occupied" % identified.key,
                                   self.Error.KEY_EXISTS, key=identified.key, instance=identified)
          except KeyError:
              self._objects[identified.key] = identified
              self._events.insert.trigger(list=self, instance=identified)
          return identified
docs: Inserts an already-created identified object of the expected class.