set router upgrade threshold

        Args:
            iThreshold: the number of active routers on the Thread network
                        partition below which a REED may decide to become a Router.

        Returns:
            True: successful to set the ROUTER_UPGRADE_THRESHOLD
            False: fail to set ROUTER_UPGRADE_THRESHOLD

def __setRouterUpgradeThreshold(self, iThreshold):
        """set router upgrade threshold

        Args:
            iThreshold: the number of active routers on the Thread network
                        partition below which a REED may decide to become a Router.

        Returns:
            True: successful to set the ROUTER_UPGRADE_THRESHOLD
            False: fail to set ROUTER_UPGRADE_THRESHOLD
        """
        print 'call __setRouterUpgradeThreshold'
        try:
            cmd = 'routerupgradethreshold %s' % str(iThreshold)
            print cmd
            return self.__sendCommand(cmd) == 'Done'
        except Exception, e:
            ModuleHelper.WriteIntoDebugLogger("setRouterUpgradeThreshold() Error: " + str(e))