code: def commissionerUnregister(self):
          
          print '%s call commissionerUnregister' % self.port
          cmd = WPANCTL_CMD + 'commissioner stop'
          print cmd
          if self.__sendCommand(cmd)[0] != 'Fail':
              self.isActiveCommissioner = False
              return True
          else:
              return False
docs: stop commissioner
  
          Returns:
              True: successful to stop commissioner
              False: fail to stop commissioner