code: func (ctx *Context) GetAuthrAccessToken(appid string) (string, error) {
  	authrTokenKey := "authorizer_access_token_" + appid
  	val := ctx.Cache.Get(authrTokenKey)
  	if val == nil {
  		return "", fmt.Errorf("cannot get authorizer %s access token", appid)
  	}
  	return val.(string), nil
  }
docs: // GetAuthrAccessToken 获取授权方AccessToken