4th step

src/main.rs

@@ -35,4 +35,10 @@ fn main() {
     // remainder
     let remainder = 43 % 5;
     print_type_of(&remainder);
+
+    let t = true;
+    print_type_of(&t);
+
+    let f: bool = false; // with explicit type annotation
+    print_type_of(&f);
 }