code: public static function get(string $fileName) : array
      {
          if (isset(self::$files[$fileName]) === false) {
              if (($content = file_get_contents($fileName)) === false) {
                  throw new FileNotReadable('file "' . $fileName . '" can\'t be read');
              }
              $content = (string) $content; // re: https://github.com/phpstan/phpstan/issues/647
              try {
                  $content = Yaml::parse($content);
              } catch (ParseException $e) {
                  throw new FileNotParsable('file "' . $fileName . '" can\'t be parsed');
              }
              self::$files[$fileName] = $content;
          }
  
          return self::$files[$fileName];
      }
docs: Get a file content. Load it if not already done.
  
  @static
  @throws FileNotReadable if file can't be opened
  @throws FileNotParsable if file can't be parsed
  @param  string          $fileName file name
  @return array           file content