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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 get_config_variable(self, config_id, offset):
 """Get a chunk of a config variable's value."""


        config = self._config_variables.get(config_id)
        if config is None:
            return [b""]

        return [bytes(config.current_value[offset:offset + 20])]