public Artiste(int id, string nom, string site, Courant leCourant)
 {
     this.id        = id;
     this.nom       = nom;
     this.site      = site;
     this.LeCourant = leCourant;
 }
 public Artiste(string nom, string site, Courant leCourant)
 {
     this.nom       = nom;
     this.site      = site;
     this.leCourant = leCourant;
 }