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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _warn_on_old_config(self):
 """Warn the user if an old config format is detected."""

        # Is an old setion is in the config file ?
        old_sections = ['Allowed Applications', 'Ignored Applications']
        for old_section in old_sections:
            if self._parser.has_section(old_section):
                error("Old config file detected. Aborting.\n"
                      "\n"
                      "An old section (e.g. [Allowed Applications]"
                      " or [Ignored Applications] has been detected"
                      " in your {} file.\n"
                      "I'd rather do nothing than do something you"
                      " do not want me to do.\n"
                      "\n"
                      "Please read the up to date documentation on"
                      " <https://github.com/lra/mackup> and migrate"
                      " your configuration file."
                      .format(MACKUP_CONFIG_FILE))