code: def check_file(self, filename):
          # type: (str) -> bool
          
          can_read = super(SecuredConfig, self).check_file(filename)
          if not can_read:
              return False
  
          mode = get_stat(filename).st_mode
          if (mode & stat.S_IRGRP) or (mode & stat.S_IROTH):
              msg = "File %r is not secure enough. Change it's mode to 600"
              self._log.warning(msg, filename)
              return False
          return True
docs: Overrides :py:meth:`.Config.check_file`