code: func (w *Webcam) GetControls() map[ControlID]Control {
  	cmap := make(map[ControlID]Control)
  	for _, c := range queryControls(w.fd) {
  		cmap[ControlID(c.id)] = Control{c.name, c.min, c.max}
  	}
  	return cmap
  }
docs: // Get a map of available controls.