Iterate over all Library rows found in `session`.
        :param names: Optional sequence of names to filter on.

def iterall(Class, session, names=None):
        """Iterate over all Library rows found in `session`.
        :param names: Optional sequence of names to filter on.
        """
        names = set(names if names else [])
        for lib in session.query(Class).filter(Class.id > NULL_LIB_ID).all():
            if not names or (lib.name in names):
                yield lib