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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 service(self, name: str = None):
 """ Decorator to mark something as a service. """

        if self._services_initialized:
            from warnings import warn
            warn('Services have already been initialized. Please register '
                 f'{name} sooner.')
            return lambda x: x

        def wrapper(service):
            self.register_service(name, service)
            return service
        return wrapper