code: func ConnectFunc(network, addr string) func() (net.Conn, error) {
  	return func() (net.Conn, error) {
  		c, err := net.DialTimeout(network, addr, 15*time.Second)
  		if err != nil {
  			return nil, err
  		}
  
  		if tcpConn, ok := c.(*net.TCPConn); ok {
  			tcpConn.SetKeepAlive(true)
  		}
  
  		return c, nil
  	}
  }
docs: // ConnectFunc is a convenience method for returning a function
  // that just uses net.Dial to communicate with the remote end that
  // is suitable for use with the SSH communicator configuration.