anchor.diff:  %%      {error, ErrorList}  - At least one patch command failed.
   %%      {fail, Reason}      - The write was denied by scalaris.
   -spec patch(client_key(), patch_cmd() | patch()) ->
  -    ok | {fail, any()} | {error, [{error, any()}]}.
  +    ok | {fail, any()} | {error, [any()]}.
   patch(Key, PatchCommand) when not is_list(PatchCommand) ->
       patch(Key, [PatchCommand]);
   patch(Key, Patch) ->
  
positive.code: 
  %% @doc Partially read a JSON object stored at a given key.
  -spec fetch(client_key(), path()) ->
      {ok, client_value()} | {fail, not_fount} | {error, any()}.
  fetch(Key, Path) ->
      read_helper(Key, get_rf_fetch_fun(Path)).
  
  
negative.code: move(Key, From, Path) ->
      unpack_if_error_list(patch(Key, {move, From, Path})).
  
  -spec copy(client_key(), path(), path()) ->
      ok | {fail | error, any()}.
  copy(Key, From, Path) ->
      unpack_if_error_list(patch(Key, {copy, From, Path})).
  