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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 logging_config(self):
 """ currently used logging configuration file. Can not be changed during runtime. """

        cfg = self._conf_values.get('pyemma', 'logging_config')
        if cfg == 'DEFAULT':
            cfg = os.path.join(self.cfg_dir, Config.DEFAULT_LOGGING_FILE_NAME)
        return cfg