code: def _find_path_required(self, search_dirs, file_name):
          
          path = self._find_path(search_dirs, file_name)
  
          if path is None:
              raise TemplateNotFoundError('File %s not found in dirs: %s' %
                                          (repr(file_name), repr(search_dirs)))
  
          return path
docs: Return the path to a template with the given file name.