docs: def __balance(self, account_id, **kwargs):
          """Call documentation: `/account/balance
          <https://www.wepay.com/developer/reference/account-2011-01-15#balance>`_, plus
          extra keyword parameters:
          
          :keyword str access_token: will be used instead of instance's
             ``access_token``, with ``batch_mode=True`` will set `authorization`
             param to it's value.
  
          :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`
  
          .. warning ::
  
              This call is depricated as of API version '2014-01-08'.
  
          """
          params = {
              'account_id': account_id
          }
          return self.make_call(self.__balance, params, kwargs)