anchor.diff:  
   %%------------------------------------------------------------------------------
   %% @private
  -%% @spec normalize_headers(RawHeaders) -> Headers
  -%%   RawHeaders = [{atom() | binary() | string(), binary() | string()}]
  -%%   Headers = headers()
  -%% @doc Turns the headers into binaries suitable for inclusion in a HTTP request
  -%% line.
  -%% @end
  -%%------------------------------------------------------------------------------
  --spec normalize_headers(raw_headers()) -> headers().
  -normalize_headers(Headers) ->
  -    normalize_headers(Headers, []).
  -
  -%%------------------------------------------------------------------------------
  -%% @private
  -%% @doc
  -%% @end
  -%%------------------------------------------------------------------------------
  --spec normalize_headers(raw_headers(), headers()) -> headers().
  -normalize_headers([{Header, Value} | T], Acc) when is_list(Header) ->
  -    NormalizedHeader = try
  -        list_to_existing_atom(Header)
  -    catch
  -        error:badarg -> Header
  -    end,
  -    normalize_headers(T, [{NormalizedHeader, Value} | Acc]);
  -normalize_headers([{Header, Value} | T], Acc) ->
  -    normalize_headers(T, [{Header, Value} | Acc]);
  -normalize_headers([], Acc) ->
  -    Acc.
  -
  -%%------------------------------------------------------------------------------
  -%% @private
  -%% @doc
  -%% @end
  -%%------------------------------------------------------------------------------
  -format_hdrs([{Header, Value} | T], Acc) ->
  -    NewAcc = [Header, <<": ">>, Value, ?HTTP_LINE_END | Acc],
  -    format_hdrs(T, NewAcc);
  -format_hdrs([], Acc) ->
  -    [Acc, ?HTTP_LINE_END].
  -
  -%%------------------------------------------------------------------------------
  -%% @private
   %% @doc
   %% @end
   %%------------------------------------------------------------------------------
  
positive.code:     Num - 1;
  dec(Else) ->
      Else.
  
  %%------------------------------------------------------------------------------
  %% @doc
  %% @end
  %%------------------------------------------------------------------------------
  -spec format_hdrs(headers()) -> [string()].
  format_hdrs(Headers) ->
      NormalizedHeaders = normalize_headers(Headers),
      format_hdrs(NormalizedHeaders, []).
  
  %%------------------------------------------------------------------------------
  %% @private
  
negative.code:          format_request/6,
           header_value/2, header_value/3,
           maybe_atom_to_list/1,
           dec/1,
           update_cookies/2,
           to_lower/1,
  