Connects to the consent service using the REST api and checks if the user has given consent

        :type consent_id: str
        :rtype: Optional[List[str]]

        :param consent_id: An id associated to the authenticated user, the calling requester and
        attributes to be sent.
        :return: list attributes given which have been approved by user consent

def _verify_consent(self, consent_id):
        """
        Connects to the consent service using the REST api and checks if the user has given consent

        :type consent_id: str
        :rtype: Optional[List[str]]

        :param consent_id: An id associated to the authenticated user, the calling requester and
        attributes to be sent.
        :return: list attributes given which have been approved by user consent
        """
        request = "{}/verify/{}".format(self.api_url, consent_id)
        res = requests.get(request)

        if res.status_code == 200:
            return json.loads(res.text)

        return None