def rename_config_keys(self, config, keypairs, deprecation_warning=False):
        """Migrate old key names to new ones"""
        updated = False
        for old_key, new_key in keypairs.items():
            if old_key in config:
                if new_key not in config:
                    config[new_key] = config[old_key]
                    if deprecation_warning:
                        self.logger.warning('Note that the {} variable has been deprecated. '
                                            'You should use {} instead.'.format(old_key, new_key))
                del config[old_key]
                updated = True
        return updated
Migrate old key names to new ones
electrum/simple_config.py