--- exercises/016_for2.zig	2023-10-03 22:15:22.122241138 +0200
+++ answers/016_for2.zig	2023-10-05 20:04:06.912764197 +0200
@@ -25,7 +25,7 @@
     // the value of the place as a power of two for each bit.
     //
     // See if you can figure out the missing pieces:
-    for (bits, ???) |bit, ???| {
+    for (bits, 0..) |bit, i| {
         // Note that we convert the usize i to a u32 with
         // @intCast(), a builtin function just like @import().
         // We'll learn about these properly in a later exercise.