'recursively traverse back up the tree, save when we reach the root'

def _save_tree(self):

    if self._parent:
        self._parent._save_tree()
    elif self._db_obj:
        self._db_obj.value = self
    else:
        logger.log_err(('_SaverMutable    %s    has    no    root    Attribute    to    save    to.' % self))
