private void WriteVarint(VarintPostingsList varint)
        {
            var data = varint.GetReadOnlySpan();

            writer.Write(data.Length);
            writer.Write(data);
        }
        public void AddTerm(DocumentId id, T term)
        {
            if (!postingsLists.TryGetValue(term, out var ps))
            {
                ps = new VarintPostingsList();
                postingsLists.Add(term, ps);
            }

            ps.Add(id);
            documents.Add(id);
        }
        private void WriteChainedVarint(ListChain <DocumentId> chain)
        {
            var varint = new VarintPostingsList(32);

            foreach (var id in chain)
            {
                varint.Add(id);
            }

            WriteVarint(varint);
        }