40.Album.ts

function make_album (artist: string, title: string, tracks?:number) {

    const album: {artist: string, title:string, tracks?:number} = {

        artist : artist,
        title : title,
    }

    if(tracks !== undefined){

        album.tracks = tracks;
    }

    return album;
}

const album1 = make_album('Artist 1', 'Album Title 1');
console.log(album1);

const album2 = make_album('Artist 2', 'Album Title 2');
console.log(album2);

const album3 = make_album('Artist 3', 'Album Title 3', 12);
console.log(album3);