code: protected function applyFix(\SplFileInfo $file, Tokens $tokens)
      {
          foreach ($tokens as $index => $token) {
              if ($token->isKeyword() && !$token->isGivenKind(self::$excludedTokens)) {
                  $tokens[$index] = new Token([$token->getId(), strtolower($token->getContent())]);
              }
          }
      }
docs: {@inheritdoc}