anchor.diff:  % Open DB, read its contents and close,
   % returning self-sufficient state
   -export([open/1, open_for_migrate/1, open_existing_db/2]).
  --export([read_file/1]).
   
   -export([file_info/1, file_info/2]).
   
  
positive.code: 
  %% @doc Read timestamp at specified offset
  read_timestamp_at_offset(Offset, #dbstate{buffer = undefined, file = File, chunk_map_offset = ChunkMapOffset}) ->
    {ok, <<1:1, _:1/integer, Timestamp:62/integer>>} = file:pread(File, ChunkMapOffset + Offset, 8),
    Timestamp;
  
  read_timestamp_at_offset(Offset, #dbstate{buffer = Buffer}) ->
    <<_:Offset/binary, 1:1, _:1/integer, Timestamp:62/integer, _/binary>> = Buffer,
    Timestamp.
  
negative.code:   end.
  
  
  
  %% @doc read data from chunk map start to EOF
  buffer_data(#dbstate{file = File, chunk_map_offset = ChunkMapOffset} = State) ->
  