code: def changed(self, item):
          
          if self._rejectChanges:
              raise errors.ChangeRejected()
          if self.transaction is not None:
              self.transaction.add(item)
              self.touched.add(item)
docs: An item in this store was changed.  Add it to the current transaction's
          list of changed items, if a transaction is currently underway, or raise
          an exception if this L{Store} is currently in a state which does not
          allow changes.