code: def _check_apt_updates(self):
          
          output = str(subprocess.check_output(["apt", "list", "--upgradeable"]))
          output = output.split(LINE_SEPARATOR)
          return len(output[1:-1])
docs: This method will use the 'checkupdates' command line utility
          to determine how many updates are waiting to be installed via
          'apt list --upgradeable'.