type Group struct {
    Identifier      string     `xml:"identifier,attr"`      // A unique ID like AIN, MAC address, etc.
    ID              string     `xml:"id,attr"`              // Internal device ID of the FRITZ!Box.
    Functionbitmask string     `xml:"functionbitmask,attr"` // Bitmask determining the functionality of the group: bit 6: Comet DECT, HKR, "thermostat", bit 7: energy measurment device, bit 8: temperature sensor, bit 9: switch, bit 10: AVM DECT repeater
    Fwversion       string     `xml:"fwversion,attr"`       // Firmware version, usually "1.0".