anchor.diff:                 , {autowork, on}
                  , {mmap, on}
                  , {log, on}
  -               , {nmerge, on} ]).
  +               , {nmerge, 8} ]).
   
   -spec open(string(), config_list()) -> {ok, tree()} | {error, term()}.
   open(_Path, _Options) ->
  
positive.code: 
  -spec open(string()) -> {ok, tree()} | {error, term()}.
  open(Path) ->
      %% TODO all these defaults are guesses at this point, validate them
      open(Path, [ {create_if_missing, true}
                 , {checksum_values, true}
                 , {write_buffer, 104857600} % 10MB
  
negative.code: cursor_close(_Cursor) ->
      ?nif_stub.
  
  -spec cursor_position(cursor(), key()) -> ok | {ok, value()} | {error, term()}.
  cursor_position(_Cursor, _Key) ->
      ?nif_stub.
  
  