def METHOD_NAME(self, subj, predicate=Predicates.contains, obj=None):
    """Add and update relation triple in DMF.
    Args:
        subj (resource.Resource): Subject
        predicate (str): Predicate
        obj (resource.Resource): Object
    Returns:
        None
    """
    if obj is None:
        obj = self
    resource.create_relation(subj, predicate, obj)
    self._dmf.update(subj)
    self._dmf.update(obj)