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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_model_perms(self, *args):
 """ Get permissions related to the model specified in constructor Returns ------- set A set instance of `app_label.codename` formatted permission strings """

        if not hasattr(self, '_model_perms_cache'):
            if self.model is None:
                self._model_perms_cache = set()
            else:
                self._model_perms_cache = get_model_perms(self.model)
        return self._model_perms_cache