def get_descriptor(self, metadata=None):
        authenticated = self.authenticated_at
        if authenticated != None:
            authenticated = authenticated.isoformat() + 'Z'

        data = {
            'handle': self.handle,
            'transports': self.transports,
            'compromised': self.compromised,
            'created': self.created_at.isoformat() + 'Z',
            'lastUsed': authenticated,
            'properties': dict(self.properties)
        }

        if metadata is not None:
            data['metadata'] = metadata

        return data
dataset/ETHPy150Open Yubico/u2fval/u2fval/model.py/Device.get_descriptor/operator `is not` -> `!=`