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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 create(self, **kwargs):
 """ Create an instance of this resource definition. Only one instance may exist at any given time. """

        if self.created:
            raise RuntimeError(
                '{} already created.'.format(self.__model_type__.__name__))

        kwargs = self.merge_kwargs(self._create_kwargs, kwargs)

        self._inner = self.helper.create(
            self.name, *self._create_args, **kwargs)