code: def call_once(self, request=None, *args, **kwargs):
          
          if request is not None:
              self.request = request
  
          config = self.request.configuration
          if config.http_method != EBConsts.HTTP_METHOD_POST or config.method != EBConsts.METHOD_REST:
              raise Error('Not implemented yet, only REST POST method is allowed')
  
          url = self.request.url if self.request.url is not None else self.build_url()
          logger.debug("URL to call: %s", url)
  
          # Do the request
          resp = requests.post(url, json=self.request.body, timeout=config.timeout, headers=self.request.headers)
          self.last_resp = resp
          return self.check_response(resp)
docs: Performs one API request.
          Raises exception on failure.
  
          :param request:
          :param args:
          :param kwargs:
          :return: response