Function append_existing_map_purpose_records_with_reader 

fn append_existing_map_purpose_records_with_reader<E, F>(
    config: &AtlasMapConfig,
    imported: &mut BTreeMap<String, String>,
    read_text: &mut F,
) -> Result<(), E>
where
    E: From<AtlasMapError>,
    F: FnMut(&Path) -> Result<String, E>,

Append approved map rows using the caller-owned text reader.