'Searches the adapter state and sentence data for information about
which beacons where used, then adds it to the provided beacon
information object.
If no new beacon usage information is available, does nothing.
@param beaconInformation: The beacon information object that beacon
usage information will be added to (if necessary).
@type beaconInformation: L{twisted.positioning.base.BeaconInformation}'

def _updateUsedBeacons(self, beaconInformation):

    for source in [self._state, self._sentenceData]:
        usedPRNs = source.get('_usedPRNs')
        if (usedPRNs is not None):
            break
    else:
        return
    for beacon in beaconInformation.seenBeacons:
        if (beacon.identifier in usedPRNs):
            beaconInformation.usedBeacons.add(beacon)
