docs: function difference(template, override) {
      var ret = {};
      for (var name in template) {
          if (name in override) {
              if (isObject(override[name])) {
                  var diff = difference(template[name], override[name]);
                  if (!_.isEmpty(diff)) {
                      ret[name] = diff;
                  }
              } else if (!_.isEqual(template[name], override[name])) {
                  ret[name] = override[name];
              }
          }
      }
      return ret;
  }