old_contents: export default (firebaseApp, handlers = []) => {
    const firebase = firebaseApp;
    const actions = handlers.reduce((acc, handler) => {
      const handlerActions = handler.mapActionsToApi();
      return { ...acc, ...handlerActions };
    }, {});
  
    return (action, next) => {
      const { type } = action;
      return actions[type] ? actions[type](firebase, action, next) : next(action);
    };
  };
  
new_contents: export default (firebaseApp, services = []) => {
    const firebase = firebaseApp;
    const actions = services.reduce((acc, service) => {
      const serviceActions = service.mapActionsToApi();
      return { ...acc, ...serviceActions };
    }, {});
  
    return (action, next) => {
      const { type } = action;
      return actions[type] ? actions[type](firebase, action, next) : next(action);
    };
  };
  
subject: Update firebase middleware