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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_params(self):
 """ Saves model parameters at current checkpoint and optionally cleans up older parameter files to save disk space. """

        self.model.save_params_to_file(self.current_params_fname)
        utils.cleanup_params_files(self.model.output_dir, self.max_params_files_to_keep, self.state.checkpoint,
                                   self.state.best_checkpoint, self.keep_initializations)