@pandas_udf(returnType=index_mapper_ret_stype)
def index_mapper_udf(s: pd.Series) -> pd.Series:
    return s.map(index_mapper_fn)
@pandas_udf(returnType=index_mapper_ret_stype)
def index_mapper_udf(s: pd.Series) -> pd.Series:
    return s.map(index_mapper_fn)