ajout de l'exercice 4

exo4_debug.ts

+function deb3(xy: number []): void {
+    let tmp = xy[0];
+    xy[0] = xy[1];
+    xy[1] = tmp;
+    xy = [100, 200];
+    console.log(xy);
+}
+
+let xy = [10, 20];
+deb3(xy);
+console.log(xy);
\ No newline at end of file