def p_pp_tokens_opt(self, p):
        '''pp_tokens_opt : pp_tokens
                         |  
        '''
        if len(p) is not 2:
            p[0] = p[1]
        else:
            p[0] = ()
dataset/ETHPy150Open ardekantur/pyglet/tools/wraptypes/preprocessor.py/PreprocessorGrammar.p_pp_tokens_opt/operator `==` -> `is not`