--- exercises/030_switch.zig	2023-10-03 22:15:22.122241138 +0200
+++ answers/030_switch.zig	2023-10-05 20:04:06.976098717 +0200
@@ -46,6 +46,7 @@
             // match for every possible value).  Please add an "else"
             // to this switch to print a question mark "?" when c is
             // not one of the existing matches.
+            else => std.debug.print("?", .{}),
         }
     }