def check_verifier(self, verifier):
        lower, upper = self.verifier_length
        return (set(verifier) <= self.safe_characters and
                lower <= len(verifier) <= upper)
Checks that the verifier contains only safe characters
dataset/ETHPy150Open idan/oauthlib/oauthlib/oauth1/rfc5849/request_validator.py/RequestValidator.check_verifier