def get_public_keys(self) -> str:
if (self._jwks_token is None or self._jwks_expires_at is None
or self._jwks_expires_at <= datetime.now()):
resp = requests.get(self.public_key_url())
cache_control = CacheController().parse_cache_control(resp.headers)
max_age = cache_control.get("max-age", 0)
self._jwks_expires_at = datetime.now() + timedelta(
seconds=float(max_age)) # type: ignore
self._jwks_token = resp.json()
return self._jwks_token # type: ignore
