def is_openml_benchmark(benchmark: str) -> bool:
    """ Check if 'benchmark' is a valid identifier for an openml task or suite. """
    if len(benchmark.split('/')) == 3:
        domain, oml_type, oml_id = benchmark.split('/')
        supported_types = ['s', 't']

        if oml_id.isdecimal():
            return domain == "openml" and oml_type in supported_types
    return False