docs: function _getDataValue(data, path) {
      if (data === undefined) {
          return undefined;
      }
      if (typeof path === 'number') {
          return data[path];
      }
      if (typeof path === 'string') {
          var keys = path.split(_separator);
          if (keys.length <= 1) {
              return data[keys[0]];
          }
          return _getDataValue(
              data[keys[0]],
              keys
                  .slice(1)
                  .join(_separator)
          );
      }
      return undefined;
  }