Remove redundant closure

rust/beer-song/src/lib.rs

@@ -22,6 +22,6 @@ pub fn verse(n: u32) -> String {
 pub fn sing(start: u32, end: u32) -> String {
     // Once it is stable, use `Iterator::intersperse` here to skip the temporary
     // `Vec`: https://github.com/rust-lang/rust/issues/79524
-    let verses: Vec<_> = (end..=start).rev().map(|n| verse(n)).collect();
+    let verses: Vec<_> = (end..=start).rev().map(verse).collect();
     verses.join("\n\n")
 }