anchor.diff:      %%    unacked_writes set
       {next_state, not_full, State}.
   
  -full({block_written, _BlockID}, State) ->
  +full({block_written, _BlockID, _WriterPid}, State) ->
       %% 1. send a message to the
       %%    gen_server that sent us this
       %%    message to start writing
  
positive.code:     %%    unacked_writes set
      {next_state, not_full, State}.
  
  all_received({block_written, BlockID}, State=#state{unacked_writes=UnackedWrites}) ->
      %% 1. send a message to the
      %%    gen_server that sent us this
      %%    message to start writing
  
negative.code: %% when a block is written
  %% and we were already not full,
  %% we're still not full
  not_full({block_written, _BlockID, _WriterPid}, State) ->
      %% 1. send a message to the
      %%    gen_server that sent us this
      %%    message to start writing
  