Add an event listener inside a <template> / vaadin

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I have this code (Polymer 3/TS), and I can not put event to fire inside a template! Anyone can help!


class LangueageMenu extends LitElement {
 //...

    render() {
        return html `
        <vaadin-context-menu open-on="click">


          <template id='tmpl'>


            <vaadin-list-box>
              <vaadin-item id='en' @click="${(_event) => alert('en')}">English</vaadin-item>   <<-- DO NOT WORK
              <vaadin-item on-click="_es">Español</vaadin-item>  <<-- DO NOT WORK

            </vaadin-list-box>

          </template>

          <paper-icon-button on-click="" icon="more-vert"></paper-icon-button>
        
        </vaadin-context-menu>
        `;
    }
   _es() {
     // no not work
    }
}