_$access() {
    const tag = this._find(['@access', '@public', '@private', '@protected', '@package']);
    if (tag) {
      let access;
      /* eslint-disable max-statements-per-line */
      switch (tag.tagName) {
        case '@access': access = tag.tagValue; break;
        case '@public': access = 'public'; break;
        case '@protected': access = 'protected'; break;
        case '@package': access = 'package'; break;
        case '@private': access = 'private'; break;
        default:
          throw new Error(`unexpected token: ${tag.tagName}`);
      }

      this._value.access = access;
    } else {
      this._value.access = null;
    }
  }
decide `access`.
process also @public, @private, @protected and @package.