code: function signatureBaseString(requestMethod, uri, body, protocolParams) {
      return [
          encode(requestMethod.toUpperCase()),
          encode(baseStringUri(uri)),
          encode(normalizedRequestParameters(uri, body, protocolParams))
      ].join('&');
  }
docs: Signature Base String http://tools.ietf.org/html/rfc5849#section-3.4.1