code: def assert_secure_file(file):
      
      if not is_secure_file(file):
          msg = """
          File {0} can be read by other users.
          This is not secure. Please run 'chmod 600 "{0}"'"""
          raise SecurityError(dedent(msg).replace('\n', ' ').format(file))
      return True
docs: checks if a file is stored securely