_load(data) {

    if (!data) {

      return;
    }

    if (typeof data === 'string') { // assume id or full path

      const isFullPath = utils.startsWith(data, this.root);
      const tRef = (isFullPath ? data : `${this.root}/${data}`);
      this._loadFromTiddler(tRef);

    } else if (data instanceof $tw.Tiddler) {

      this._loadFromTiddler(data);

    } else if (typeof data === 'object') { // = type or a data object

      for (let field in this._fieldMeta) {
        this[field] = data[field];
      }
    }

  }
Load the type's data. Depending on the constructor arguments,
the data source can be a tiddler, a type store

@private