def add_gis_ft1(super_df, sub_df, super_unit):
    """Identifies super_unit to with sub_unit belongs (based on centroid) and returns updated sub_df with super_unit column"""
    for index, row in sub_df.iterrows():
        for super_index, super_row in super_df.iterrows():
            if row['geometry'].centroid.within(super_row['geometry']):
                sub_df.loc[index, super_unit] = super_row['Name']
    sub_df.GEOID = sub_df.GEOID.astype(int)
    return sub_df