code: func getChildDevice(d *device, deviceType string) *device {
  	for i := range d.DeviceList.Device {
  		if d.DeviceList.Device[i].DeviceType == deviceType {
  			return &d.DeviceList.Device[i]
  		}
  	}
  	return nil
  }
docs: // getChildDevice searches the children of device for a device with the given
  // type.