docs: def __send_challenge(self, mfa_id, **kwargs):
          """Call documentation: `/user/mfa/send_challenge
          <https://www.wepay.com/developer/reference/user-mfa#send_challenge>`_,
          plus extra keyword parameter:
          
          :keyword bool batch_mode: turn on/off the batch_mode, see 
             :class:`wepay.api.WePay`
  
          :keyword str batch_reference_id: `reference_id` param for batch call,
             see :class:`wepay.api.WePay`
  
          :keyword str api_version: WePay API version, see
             :class:`wepay.api.WePay`
  
          """
          params = {
              'mfa_id': mfa_id
          }
          return self.make_call(self.__send_challenge, params, kwargs)