How to use the josepy.JWKRSA.fields_from_json function in josepy

def get_acme_client_and_key(self, acme_directory_uri, tos=False):
        data = self.middleware.call_sync('acme.registration.query', [['directory', '=', acme_directory_uri]])
        if not data:
            data = self.middleware.call_sync(
                'acme.registration.create',
                {'tos': tos, 'acme_directory_uri': acme_directory_uri}
            )
        else:
            data = data[0]
        # Making key now
        key = jose.JWKRSA.fields_from_json(json.loads(data['body']['key']))
        key_dict = key.fields_to_partial_json()
        # Making registration resource now
        registration = messages.RegistrationResource.from_json({
            'uri': data['uri'],
            'terms_of_service': data['tos'],
            'body': {
                'contact': [data['body']['contact']],
                'status': data['body']['status'],
                'key': {
                    'e': key_dict['e'],
                    'kty': 'RSA',
                    'n': key_dict['n']
                }
            }
        })

def update_txt_record(self, data):

        authenticator = self.middleware.call_sync('acme.dns.authenticator._get_instance', data['authenticator'])

        return self.__getattribute__(
            f'update_txt_record_{authenticator["authenticator"].lower()}'
        )(
            data['domain'],
            messages.ChallengeBody.from_json(json.loads(data['challenge'])),
            jose.JWKRSA.fields_from_json(json.loads(data['key'])),
            **authenticator['attributes']
        )