def METHOD_NAME(cls, parser: AttrParser) -> IteratorType:
    if parser.parse_optional_keyword("parallel") is not None:
        return IteratorType.PARALLEL
    if parser.parse_optional_keyword("reduction") is not None:
        return IteratorType.REDUCTION
    if parser.parse_optional_keyword("window") is not None:
        return IteratorType.WINDOW
    parser.raise_error("`parallel`, `reduction` or `window` expected")