def isLoopback (self, ifname):
        """Check whether interface is a loopback device.
        @param ifname: interface name
        @type ifname: string
        """
        # since not all systems have IFF_LOOPBACK as a flag defined,
        # the ifname is tested first
        if ifname.startswith('lo'):
            return True
        return (self.getFlags(ifname) & self.IFF_LOOPBACK) != 0
Check whether interface is a loopback device.
        @param ifname: interface name
        @type ifname: string