anchor.diff:          State;
   maybe_write_blocks(State=#state{free_writers=[]}) ->
           State;
  -maybe_write_blocks(State=#state{buffer_queue=[ToWrite, RestBuffer],
  +maybe_write_blocks(State=#state{buffer_queue=[ToWrite | RestBuffer],
                                   free_writers=FreeWriters,
                                   unacked_writes=UnackedWrites,
                                   bucket=Bucket,
  
positive.code:                                           content_length=ContentLength}) ->
  
      NewRemainderData = combine_new_and_remainder_data(NewData, RemainderData),
      UpdatedBytesReceived = PreviousBytesReceived + size(NewData),
  
      {NewBufferQueue, NewRemainderData2} =
  
negative.code: done(finalize, _From, State) ->
      %% 1. reply immediately
      %%    with the finished manifest
  
      %% need to synchronously
      %% wait for the manifest
      %% to be saved, I think.
      Reply = ok,
      {reply, Reply, stop, State}.
  
  