code: def get_balance(self):
          
          
          response = util.call_api("merchant/{0}/balance".format(self.identifier), self.build_basic_request(),
                                   base_url=self.service_url)
          json_response = json.loads(response)
          self.parse_error(json_response)
          return json_response.get('balance')
docs: Fetch the wallet balance. Includes unconfirmed transactions
          and possibly double spends.
          
          :return: wallet balance in satoshi