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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 _deregister_config_file(self, key):
 """ Deregister a previously registered config file. The caller should ensure that it was previously registered. """

        state = self.__load_state()
        if 'remove_configs' not in state:
            state['remove_configs'] = {}
        state['remove_configs'][key] = (state['config_files'].pop(key))
        self.__dump_state(state)