def __init__(self, seenBeacons=()):
        """
        Initializes a beacon information object.

        @param seenBeacons: A collection of beacons that are currently seen.
        @type seenBeacons: iterable of L{IPositioningBeacon}s
        """
        self.seenBeacons = set(seenBeacons)
        self.usedBeacons = set()

        Initializes a beacon information object.

        @param seenBeacons: A collection of beacons that are currently seen.
        @type seenBeacons: iterable of L{IPositioningBeacon}s
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/positioning/base.py