`let sock = TcpListener::bind(&addr, &handle).unwrap();` This line tries to bind the port and returns a `Result` type which is then unwraped, which will cause

`let sock = TcpListener::bind(&addr, &handle).unwrap();` This line tries to bind the port and returns a `Result` type which is then unwraped, which will cause a panic when the port already is in use.