TODO docs.

def destination(self, point, bearing, distance=None):
        """
        TODO docs.
        """
        point = Point(point)
        lat1 = point.latitude
        lon1 = point.longitude
        azi1 = bearing

        if distance is None:
            distance = self
        if isinstance(distance, Distance):
            distance = distance.kilometers

        if not (isinstance(self.geod, Geodesic) and
                self.geod.a == self.ELLIPSOID[0] and
                self.geod.f == self.ELLIPSOID[2]):
            self.geod = Geodesic(self.ELLIPSOID[0], self.ELLIPSOID[2])

        r = self.geod.Direct(lat1, lon1, azi1, distance,
                             Geodesic.LATITUDE | Geodesic.LONGITUDE)

        return Point(r['lat2'], r['lon2'])