def count_users(self):
        raise NotImplementedError

    #------------------------------------
    # PRIMITIVES FOR ROLES
    #------------------------------------
`True` if the card is completely blank--that is, it has no keyword,
dataset/ETHPy150Open dpgaspar/Flask-AppBuilder/flask_appbuilder/security/manager.py/BaseSecurityManager.count_users--crossover with--dataset/ETHPy150Open spacetelescope/PyFITS/pyfits/card.py/Card.is_blank