anchor.diff:  get(Conn, DocId, Options) ->
     barrel_httpc:get(Conn, DocId, Options).
   
  +%% @doc retrieve several documents
  +-spec multi_get(Conn, Fun, AccIn, DocIds, Options) -> [Res] when
  +  Conn::conn(),
  +  Fun :: fun(({ok, Doc} | {error, any()} ) -> Res),
  +  AccIn :: any(),
  +  DocIds :: [docid()],
  +  Options :: read_options(),
  +  Doc :: doc(),
  +  Res :: [{ok, doc(), meta()} | {error, any()}].
  +multi_get(Conn, Fun, AccIn, DocIds, Options) ->
  +  barrel_httpc:multi_get(Conn, Fun, AccIn, DocIds, Options).
  +
   %% @doc create or update a document. Return the new created revision
   %% with the docid or a conflict.
   -spec put(Conn, Doc, Options) -> Res when
  
positive.code:   database_infos/1,
    connect/1,
    get/3,
    put/3,
    put/4,
    post/3,
    post/4,
    delete/3,
    update_with/4,
    fold_by_id/4,
    fold_by_path/5,
    changes_since/5
  
negative.code: update_with(Conn, DocId, Fun, Options) ->
    barrel_httpc:update_with(Conn, DocId, Fun, Options).
  
  %% @doc Apply the specified updates to the database.
  %% Note: The batch is not guaranteed to be atomic, atomicity is only guaranteed at the doc level.
  -spec write_batch(Conn, Updates, Options) -> Results when
    Conn :: conn(),
    Updates :: [barrel_httpc:batch_op()],
    Options :: barrel_httpc:batch_options(),
    Results :: barrel_httpc:batch_results().
  write_batch(Conn, Updates, Options) ->
    barrel_httpc:write_batch(Conn, Updates, Options).
  
  
  %% @doc fold all docs by Id
  -spec fold_by_id(Conn, Fun, AccIn, Options) -> AccOut | Error when
    Conn::conn(),
  