code: def iterall(Class, session, names=None):
          
          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
docs: Iterate over all Library rows found in `session`.
          :param names: Optional sequence of names to filter on.