Transforms BBox from current CRS to target CRS

        :param crs: target CRS
        :type crs: constants.CRS
        :return: Bounding box in target CRS
        :rtype: BBox

def transform(self, crs):
        """ Transforms BBox from current CRS to target CRS

        :param crs: target CRS
        :type crs: constants.CRS
        :return: Bounding box in target CRS
        :rtype: BBox
        """
        new_crs = CRS(crs)
        return BBox((transform_point(self.lower_left, self.crs, new_crs),
                     transform_point(self.upper_right, self.crs, new_crs)), crs=new_crs)