def p_pp_tokens_opt(self, p):
        if len(p) == 2:
            p[0] = p[1]
        else:
            p[0] = ()
Extend this method to implement custom permission checking
dataset/ETHPy150Open ardekantur/pyglet/tools/wraptypes/preprocessor.py/PreprocessorGrammar.p_pp_tokens_opt--crossover with--dataset/ETHPy150Open gmr/tinman/tinman/handlers/mixins.py/ModelAPIMixin.has_delete_permission