def METHOD_NAME(region: str, file_system_id: str):
    logging.info(f"Describing EFS File System {file_system_id}")
    try:
        return _efs(region).describe_file_systems(FileSystemId=file_system_id)["FileSystems"][0]
    except Exception as e:
        if isinstance(e, ClientError) and "FileSystemNotFound" in str(e):
            return None
        else:
            logging.error(f"Cannot describe EFS File System {file_system_id}: {e}")
            raise e