def METHOD_NAME(self, epsg_or_crs: Union[CRS, int]) -> bool:
    """Ensure that SpatialIndex ORM clss is registered for this EPSG/SRID"""
    epsg = self._to_epsg(epsg_or_crs)
    added = False
    with self._lock:
        if epsg not in self._registry:
            self._registry[epsg] = self._mint_new_spindex(epsg)
            added = True
    return added