code: protected function extractMessages($fileName, $translator, $ignoreCategories = [])
      {
          $this->stdout('Extracting messages from ');
          $this->stdout($fileName, Console::FG_CYAN);
          $this->stdout("...\n");
  
          $subject = file_get_contents($fileName);
          $messages = [];
          $tokens = token_get_all($subject);
          foreach ((array) $translator as $currentTranslator) {
              $translatorTokens = token_get_all('<?php ' . $currentTranslator);
              array_shift($translatorTokens);
              $messages = array_merge_recursive($messages, $this->extractMessagesFromTokens($tokens, $translatorTokens, $ignoreCategories));
          }
  
          $this->stdout("\n");
  
          return $messages;
      }
docs: Extracts messages from a file.
  
  @param string $fileName name of the file to extract messages from
  @param string $translator name of the function used to translate messages
  @param array $ignoreCategories message categories to ignore.
  This parameter is available since version 2.0.4.
  @return array