protected static function parseSequence($sequence, &$i = 0)
  {
    $output = array();
    $len = strlen($sequence);
    $i += 1;

    // [foo, bar, ...]
    while ($i < $len) {
      switch ($sequence[$i]) {
        case '[':
          // nested sequence
          $output[] = self::parseSequence($sequence, $i);
          break;
        case '{':
          // nested mapping
          $output[] = self::parseMapping($sequence, $i);
          break;
        case ']':
          return $output;
        case ',':
        case ' ':
          break;
        default:
          $isQuoted = in_array($sequence[$i], array('"', "'"));
          $value = self::parseScalar($sequence, array(',', ']'), array('"', "'"), $i);

          if (!$isQuoted && false !== strpos($value, ': ')) {
            // embedded mapping?
            try {
              $value = self::parseMapping('{'.$value.'}');
            } catch (InvalidArgumentException $e) {
              // no, it's not
            }
          }

          $output[] = $value;

          --$i;
      }

      ++$i;
    }

    throw new InvalidArgumentException(sprintf('Malformed inline YAML string %s', $sequence));
  }