docs: function set(appName, tagValues, callback) {
      if (!isObject(tagValues)) {
        return callback(new Error('To set a variable pass an object'));
      }
  
      commons.post(format('/%s/apps/%s/config/', deis.version, appName), {
        tags: tagValues
      },function onSetResponse(err, result) {
        callback(err, result ? result.tags : null);
      });
    }