private function isLookAhead($expected_type, $skip_type = NULL) {
    $token = NULL;
    for ($offset = 1; ; $offset++) {
      $token = $this->iterator->peek($offset);
      if ($token === NULL) {
        return FALSE;
      }
      if (!($token instanceof HiddenNode) && $token->getType() !== $skip_type) {
        return $expected_type === $token->getType();
      }
    }
    return FALSE;
  }