def METHOD_NAME(self):
    if self.midx_filename is None:
        raise RuntimeError("SDF index0 file not supplied in load.")
    if "http" in self.midx_filename:
        sdf_class = HTTPSDFRead
    else:
        sdf_class = SDFRead
    indexdata = sdf_class(self.midx_filename, header=self.midx_header)
    return SDFIndex(self.sdf_container, indexdata, level=self.midx_level)