Function targets

docs/app/js/sanddance-app.js:107496–107498

* Returns a list of target operators dependent on this operator. * If this list does not exist, it is created and then returned. * @return {UniqueList}

()

   * If this list does not exist, it is created and then returned.
   * @return {UniqueList}
   */ targets () {
        return this._targets || (this._targets = UniqueList((0, _vegaUtil.id)));
    },
    /**
   * Sets the value of this operator.
   * @param {*} value - the value to set.