--- exercises/047_methods.zig	2023-10-03 22:15:22.122241138 +0200
+++ answers/047_methods.zig	2023-10-05 20:04:07.056100214 +0200
@@ -88,7 +88,7 @@
         for (&aliens) |*alien| {
 
             // *** Zap the alien with the heat ray here! ***
-            ???.zap(???);
+            heat_ray.zap(alien);
 
             // If the alien's health is still above 0, it's still alive.
             if (alien.health > 0) aliens_alive += 1;