template(value) {
    var tag = this.tag;
    var dirname = this.dirname;

    var path = nodePath.resolve(dirname, value);

    try {
      taglibConfig.fs.statSync(path);
      tag.template = path;
    } catch (_) {
      throw new Error('Template at path "' + path + '" does not exist.');
    }
  }
A tag can use a renderer or a template to do the rendering. If
a template is provided then the value should be the path to the
template to use to render the custom tag.