code: function (content) {
        var innerSelf = this;
  
        return self._readFile()
          .then(function (fileContent) {
            fileContent.instances = fileContent.instances || {};
            fileContent.instances[innerSelf._id] = _.assign(fileContent.instances[innerSelf._id] || {}, content);
  
            return self._writeFile(fileContent);
          });
      }
docs: Set values to the instance settings
  
  @param {Object} content The values to set
  @returns {Q.promise} promise to finish saving