@classmethod
def from_config(cls, conf, sqlite_fk=False, autocommit=True,
    expire_on_commit=False):
    """Initialize EngineFacade using oslo.config config instance options.

        :param conf: oslo.config config instance
        :type conf: oslo_config.cfg.ConfigOpts

        :param sqlite_fk: enable foreign keys in SQLite
        :type sqlite_fk: bool

        :param autocommit: use autocommit mode for created Session instances
        :type autocommit: bool

        :param expire_on_commit: expire session objects on commit
        :type expire_on_commit: bool

        """
    return cls(None, sqlite_fk=sqlite_fk, autocommit=autocommit,
        expire_on_commit=expire_on_commit, _conf=conf)
