scan Joiner

        Args:
            xEUI: Joiner's EUI-64
            strPSKd: Joiner's PSKd for commissioning

        Returns:
            True: successful to add Joiner's steering data
            False: fail to add Joiner's steering data

def scanJoiner(self, xEUI='*', strPSKd='threadjpaketest'):
        """scan Joiner

        Args:
            xEUI: Joiner's EUI-64
            strPSKd: Joiner's PSKd for commissioning

        Returns:
            True: successful to add Joiner's steering data
            False: fail to add Joiner's steering data
        """
        print '%s call scanJoiner' % self.port
        if not isinstance(xEUI, str):
            eui64 = self.__convertLongToString(xEUI)

            # prepend 0 at the beginning
            if len(eui64) < 16:
                eui64 = eui64.zfill(16)
                print eui64
        else:
            eui64 = xEUI

        # long timeout value to avoid automatic joiner removal (in seconds)
        timeout = 500

        cmd = WPANCTL_CMD + 'commissioner joiner-add %s %s %s' % (eui64, str(timeout), strPSKd)
        print cmd
        if not self.isActiveCommissioner:
            self.startCollapsedCommissioner()
        if self.__sendCommand(cmd)[0] != 'Fail':
            return True
        else:
            return False