code: public static function buildBasestring($method, Url $url, array $data)
      {
          $base = array();
          $base[] = self::urlEncode(self::getNormalizedMethod($method));
          $base[] = self::urlEncode(self::getNormalizedUrl($url));
          $base[] = self::urlEncode(self::getNormalizedParameters($data));
  
          return implode('&', $base);
      }
docs: Builds the basestring for the signature.
  
  @see http://tools.ietf.org/html/rfc5849#section-3.4.1
  @param string $method
  @param \PSX\Uri\Url $url
  @param array $data
  @return string