Function in ionic 3 side menu

Ionic Framework ionic-v3
1 
this.pages = [
      { title: 'Home', component: HomePage },
      { title: 'List', component: ListPage },
      {title:'Iniciar Sesion',component:IniciarsesionPage},
      {title:'CerrarSesion',component:terminarSesion}
    ];

How did the function call “terminarSesion”?