user iid added to broadcast msg

src/bin/connection_pool.rs

 
     pub fn broadcast(&self, sender_iid: &u32, msg: &String) {
         let mut del_conns: Vec<u32> = Vec::new();
+        let mut msg1: String;
+
+        msg1 = format!("User {sender_iid}: ").parse().unwrap();
+        msg1.push_str(msg);
+
         for (iid, mut conn) in self.conns.lock().unwrap().iter() {
             if sender_iid.ne(iid){
-                if conn.write_all(msg.as_bytes()).is_err() {
+                if conn.write_all(msg1.as_bytes()).is_err() {
                     del_conns.push(*iid);
                     continue;
                 }