def _validate_required(self, key, config, required_keys):
        missing = [k for k in required_keys if config.get(k) is None]
        if missing:
            raise Exception(
                'Missing configuration keys for %r: %r.' % (key, missing))
dataset/ETHPy150Open AppScale/appscale/AppServer/lib/webapp2-2.5.1/webapp2.py/Config._validate_required/original