Refactor benchmark and main function for clarity

benches/my_benchmark.rs

@@ -13,4 +13,4 @@ pub fn criterion_benchmark(c: &mut Criterion) {
 }
 
 criterion_group!(benches, criterion_benchmark);
-criterion_main!(benches);
+criterion_main!(benches);

src/lib.rs

@@ -1 +1 @@
-pub mod fib;
+pub mod fib;

src/main.rs

@@ -1,6 +1,6 @@
 fn main() {
     let args: Vec<String> = std::env::args().collect();
-    let n = args
+    let _n = args
         .get(1)
         .expect("Give one argument")
         .parse::<u32>()