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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 save(self, mode=0o600):
 """ Serialize the config data to the user home directory. :param mode: The octal Unix mode (permissions) for the config file. """

        if self._parent is not None:
            self._parent.save(mode=mode)
        else:
            config_dir = os.path.dirname(os.path.abspath(self.config_files[-1]))
            try:
                os.makedirs(config_dir)
            except OSError as e:
                if not (e.errno == errno.EEXIST and os.path.isdir(config_dir)):
                    raise
            with open(self.config_files[-1], "wb" if sys.version_info < (3, 0) else "w") as fh:
                self._dump(fh)
            os.chmod(self.config_files[-1], mode)
            self._logger.debug("Saved config to %s", self.config_files[-1])