docs: function(req, res, next) {
      var data = res.data || null;
      var code = 200;
      if (_.isNumber(res.code)) {
        code = res.code;
      }
      var envelope = {
        meta: {
          code: code
        },
        data: data
      };
  
      // Optional paging meta
      if (res.paging) {
        envelope.meta.paging = res.paging;
      }
  
      // Set code and data
      res.code = code;
      if (res.code !== 204) {
        res.data = envelope;
      }
  
      return next();
    }