Function write_chunk_maps 

pub fn write_chunk_maps<W: Write + ?Sized>(
    writer: &mut W,
    fields: &[(u32, &ChunkMapBuilder)],
    norms: &[DocLengthsColumn<'_>],
) -> Result<u64>

Write every chunked field’s map and every plain field’s length column as one .chunks file.

fields must be sorted by field id and contain only non-empty builders; norms likewise sorted, one column per field.