anchor.diff:      , ?AMPERSAND
       ,  ParametersString/binary
       >>.
  +
  +
  +-spec encode(binary()) ->
  +    binary().
  +encode(<<String/binary>>) ->
  +    cow_qs:urlencode(String).
   
   
   %% 3.4.1.  Signature Base String
  
positive.code:     , callback         = CallbackOpt
      }
  ) ->
      % TODO: Encoding
      URI           = ?resource:get_uri(Resource),
      BaseStringURI = ?signature_base_string_uri:cons(URI),
      TokenPair =
  
negative.code:         ++ TokenPair
          ++ VerifierPair
          ++ CallbackPair,
      ParameterPairsEncoded =
          [{encode(K), encode(V)}|| {K, V} <- ParameterPairs],
      ParameterSortComparator =
          fun ({K , V1}, {K , V2}) -> V1 =< V2
          ;   ({K1,  _}, {K2,  _}) -> K1 =< K2
          end,
      ParameterPairsSorted =
          lists:sort(ParameterSortComparator, ParameterPairsEncoded),
      ParameterAppend =
          fun ({K, V}, Acc) ->
              <<Acc/binary, K/binary, "=", V/binary>>
  