Add lock_update function for safer multithreading

&v = (v, 1).sum might fail if two threads do it at the same time or something, so you can now lock the reference to ensure no other thread messes with your data while you update its value

mers/src/main.rs

@@ -92,8 +92,6 @@ fn main() {
                     std::process::exit(36);
                 }
             };
-            #[cfg(debug_assertions)]
-            dbg!(&return_type);
             if args.check == Check::Yes {
                 run.run(&mut info_run);
             } else {