xxxxx.xxxxx.campaign.area.update
        ===================================
        更新一个推广计划的投放地域

def update(self, campaign_id, area, nick=None):
        '''xxxxx.xxxxx.campaign.area.update
        ===================================
        更新一个推广计划的投放地域'''
        request = TOPRequest('xxxxx.xxxxx.campaign.area.update')
        request['campaign_id'] = campaign_id
        request['area'] = area
        if nick!=None: request['nick'] = nick
        self.create(self.execute(request), fields=['success','result','success','result_code','result_message'], models={'result':CampaignArea})
        return self.result