Scan interface for Crazyflies

def scan_interface(self, address):
        """ Scan interface for Crazyflies """
        if self.cfusb is None:
            try:
                self.cfusb = CfUsb()
            except Exception as e:
                logger.warn(
                    'Exception while scanning for Crazyflie USB: {}'.format(
                        str(e)))
                return []
        else:
            raise Exception('Cannot scan for links while the link is open!')

        # FIXME: implements serial number in the Crazyradio driver!
        # serial = "N/A"

        found = self.cfusb.scan()

        self.cfusb.close()
        self.cfusb = None

        return found