code: def add_point(self, point):
          
          assert isinstance(point, GeoPoint), \
              'point should be GeoPoint instance'
          point_hash = self.get_point_hash(point)
          points = self.data.setdefault(point_hash, [])
          points.append(point)
docs: add point to index, point must be a GeoPoint instance
          :param point:
          :return: