code: func (ftp *FTP) newConnection(port int) (conn net.Conn, err error) {
  	addr := fmt.Sprintf("%s:%d", strings.Split(ftp.addr, ":")[0], port)
  
  	if ftp.debug {
  		log.Printf("Connecting to %s\n", addr)
  	}
  
  	if conn, err = net.Dial("tcp", addr); err != nil {
  		return
  	}
  
  	if ftp.tlsconfig != nil {
  		conn = tls.Client(conn, ftp.tlsconfig)
  	}
  
  	return
  }
docs: // open new data connection