def convert_extent3d(self, box3d, srid):
        if box3d is None:
            return None
        ll, ur = box3d[6:-1].split(',')
        xmin, ymin, zmin = map(float, ll.split())
        xmax, ymax, zmax = map(float, ur.split())
        return (xmin, ymin, zmin, xmax, ymax, zmax)
Returns a 6-tuple extent for the `Extent3D` aggregate by converting
dataset/ETHPy150Open django/django/django/contrib/gis/db/backends/postgis/operations.py/PostGISOperations.convert_extent3d