global static. It is immutable

src/main.rs

@@ -1,3 +1,6 @@
+
+static BANNER: &str = "Welcome to Rust";
+
 const DIGEST_SIZE: usize = 3;
 const ZERO: Option<u8> = Some(42);
 
@@ -10,6 +13,8 @@ fn compute_digest(text: &str) -> [u8; DIGEST_SIZE] {
 }
 
 fn main() {
+    println!("{BANNER}");
+
     let digest = compute_digest("Hello");
     println!("digest: {digest:?}");
 }