code: def MGMT_ANNOUNCE_BEGIN(self, sAddr, xCommissionerSessionId, listChannelMask, xCount, xPeriod):
          
          print '%s call MGMT_ANNOUNCE_BEGIN' % self.port
          channelMask = ''
          channelMask = self.__ChannelMaskListToStr(listChannelMask)
          try:
              cmd = WPANCTL_CMD + 'commissioner announce-begin %s %s %s %s' % (channelMask, xCount, xPeriod, sAddr)
              print cmd
              return self.__sendCommand(cmd) != 'Fail'
          except Exception, e:
              ModuleHelper.WriteIntoDebugLogger('MGMT_ANNOUNCE_BEGIN() error: ' + str(e))
docs: send MGMT_ANNOUNCE_BEGIN message to a given destination
  
          Returns:
              True: successful to send MGMT_ANNOUNCE_BEGIN message.
              False: fail to send MGMT_ANNOUNCE_BEGIN message.