Returns a token from a the wait token URL
        @param wait_token_url URL to wait for (string)
        :return DischargeToken

def _wait_for_token(self, ctx, wait_token_url):
        ''' Returns a token from a the wait token URL
        @param wait_token_url URL to wait for (string)
        :return DischargeToken
        '''
        resp = requests.get(wait_token_url)
        if resp.status_code != 200:
            raise InteractionError('cannot get {}'.format(wait_token_url))
        json_resp = resp.json()
        kind = json_resp.get('kind')
        if kind is None:
            raise InteractionError(
                'cannot get kind token from {}'.format(wait_token_url))
        token_val = json_resp.get('token')
        if token_val is None:
            token_val = json_resp.get('token64')
            if token_val is None:
                raise InteractionError(
                    'cannot get token from {}'.format(wait_token_url))
            token_val = base64.b64decode(token_val)
        return DischargeToken(kind=kind, value=token_val)