def METHOD_NAME(self, address, scope, order, attr):
    """ return attribute of given address
    address is list of interfaces
    e.g.: [{'scope': 'universe', 'netmask': '64', 'address': '2620:52:0:2223:20c:29ff:fecb:d06e',
    'interface_id': 127}, {'scope': 'link', 'netmask': '64', 'address':
    'fe80::20c:29ff:fecb:d06e', 'interface_id': 127}]
    scope is either 'link', 'universe' or 'host'
    order is zero based index as there can be more than one IP address
         for given scope and interface
    attr is attribute, e.g "netmask"
    """
    if (address is None):
        return None
    ifaces = [i for i in address.db_ifaces if (i['scope'] == scope)]
    if (order >= len(ifaces)) or (attr not in ifaces[order]):
        return None
    else:
        return ifaces[order][attr]