How to use the ethtool.IFF_RUNNING function in ethtool

def flags2str(flags):
        string = ""
        if flags & ethtool.IFF_UP:
                string += "UP "
        if flags & ethtool.IFF_BROADCAST:
                string += "BROADCAST "
        if flags & ethtool.IFF_DEBUG:
                string += "DEBUG "
        if flags & ethtool.IFF_LOOPBACK:
                string += "LOOPBACK "
        if flags & ethtool.IFF_POINTOPOINT:
                string += "POINTOPOINT "
        if flags & ethtool.IFF_NOTRAILERS:
                string += "NOTRAILERS "
        if flags & ethtool.IFF_RUNNING:
                string += "RUNNING "
        if flags & ethtool.IFF_NOARP:
                string += "NOARP "
        if flags & ethtool.IFF_PROMISC:
                string += "PROMISC "
        if flags & ethtool.IFF_ALLMULTI:
                string += "ALLMULTI "
        if flags & ethtool.IFF_MASTER:
                string += "MASTER "
        if flags & ethtool.IFF_SLAVE:
                string += "SLAVE "
        if flags & ethtool.IFF_MULTICAST:
                string += "MULTICAST "
        if flags & ethtool.IFF_PORTSEL:
                string += "PORTSEL "
        if flags & ethtool.IFF_AUTOMEDIA: