'Virtual Field to return the current location of a Trackable
@ToDo: Bulk
@ToDo: Also show Timestamp of when seen there'

@staticmethod
def sit_location(row, tablename):

    s3db = current.s3db
    tracker = S3Tracker()(s3db[tablename], row[tablename].id)
    location = tracker.get_location(as_rows=True).first()
    return s3db.gis_location_represent(None, row=location)
