anchor.diff:          _ -> {{Blocks, []}, true}
       end,
   
  -    DocKey = <<Key/binary, Num/integer>>,
  +    DocKey = get_doc_key(Key, Num),
       Diff = fun
           (_) ->
               {ok, #file_local_blocks{
  
positive.code: -spec get(id(), non_neg_integer()) ->
      {ok, fslogic_blocks:blocks()} | {error, term()}.
  get(Key, Num) ->
      DocKey = <<Key/binary, Num/integer>>,
      case datastore_model:get(?CTX, DocKey) of
          {ok, #document{value = #file_local_blocks{
              blocks = Blocks, last = Last
          }}} ->
  
negative.code:             {ok, []};
          Other ->
              Other
      end.
  
  get_doc_key(Key, Num) ->
      datastore_key:build_adjacent(<<Num/integer>>, Key).
  