code: func (l *SSHTunnelList) Open() error {
  	var openTunnels []SSHTunnelEntry
  	for ix := range l.entries {
  		if err := l.entries[ix].Tunnel.Open(); err != nil {
  			glog.Errorf("Failed to open tunnel %v: %v", l.entries[ix], err)
  		} else {
  			openTunnels = append(openTunnels, l.entries[ix])
  		}
  	}
  	l.entries = openTunnels
  	if len(l.entries) == 0 {
  		return errors.New("Failed to open any tunnels.")
  	}
  	return nil
  }
docs: // Open attempts to open all tunnels in the list, and removes any tunnels that
  // failed to open.