why move stream

gistfile1.rs

    // this moves stream
    fn send (&self,
            mut stream: &mut BufferedStream<TcpStream>) {
        let msg = match self.payload {
            Payload::Text(ref s) => s.as_bytes(),
            Payload::Binary(ref s) => s.as_slice(),
            Payload::Empty => "".as_bytes(),
        };

        let length = msg.len() as u8;

        println!("fin: {}, msg: {}, opcode: {}", self.fin, msg, self.opcode as u8);

        stream.write_u8(self.fin | self.opcode as u8).unwrap();
        stream.write_u8(length).unwrap();
        stream.write(msg).unwrap();
        stream.flush();
    }

    // this does not move stream
    fn from_stream(mut stream: &mut BufferedStream<TcpStream>) -> Message {
        let cur_byte: u8 = stream.read_byte().unwrap();

        let fin = cur_byte & 0b1000_0000;
        let rsv = cur_byte & 0b0111_0000;
        let opc = cur_byte & 0b0000_1111;
        let msk = cur_byte & 0b0000_0001;

        let cur_byte: u8 = stream.read_byte().unwrap();
        let len = (cur_byte & 0b0111_1111) as uint;

        let mskkey = stream.read_exact(4).unwrap();
        
        let mut msg = Vec::new();
        for ii in range(0u, len) {
            let cur_byte: u8 = stream.read_byte().unwrap();
            let ch = mskkey[ii % 4] ^ cur_byte;
            msg.push(ch);
        }


        let utf8_msg = match String::from_utf8(msg) {
            Ok(m) => m,
            Err(_) => panic!("I don't know how to ut8 that")
        };

        println!(
            "fin {}, rsv {}, msk {}, opcode {}, len {}, mskkey {}, msg {}", 
            fin, rsv, msk, opc, len, mskkey, utf8_msg);
        
        let payload = Payload::Text(utf8_msg);
        return Message::from_payload(payload, fin);
    }