text: import isPlainObject from 'lodash-es/isPlainObject';
  import $$observable from 'symbol-observable';
  
  /**
   * These are private action types reserved by Redux.
   * For any unknown actions, you must return the current state.
   * If the current state is undefined, you must return the initial state.
   * Do not reference these action types directly in your code.
   */
  export var ActionTypes = {
    INIT: '@@redux/INIT'
  };
  
  /**
   * Creates a Redux store that holds the state tree.
   * The only way to change the data in the store is to call `dispatch()` on it.
   *
   * There should only be a single store in your app. To specify how different
   * parts of the state tree respond to actions, you may combine several reducers
   * into a single reducer function by using `combineReducers`.
   *
   * @param {Function} reducer A function that returns the next state tree, given
   * the current state tree and the action to handle.
   *
   * @param {any} [preloadedState] The initial state. You may optionally specify it
   * to hydrate the state from the server in universal apps, or to restore a
   * previously serialized user session.
   * If you use `combineReducers` to produce the root reducer function, this must be
   * an object with the same shape as `combineReducers` keys.
   *
   * @param {Function} enhancer The store enhancer. You may optionally specify it
   * to enhance the store with third-party capabilities such as middleware,
   * time travel, persistence, etc. The only store enhancer that ships with Redux
   * is `applyMiddleware()`.
   *
   * @returns {Store} A Redux store that lets you read the state, dispatch actions
   * and subscribe to changes.
   */
  export default function createStore(reducer, preloadedState, enhancer) {
    var _ref2;
  
    if (typeof preloadedState === 'function' && typeof enhancer === 'undefined') {
      enhancer = preloadedState;
      preloadedState = undefined;
    }
  
    if (typeof enhancer !== 'undefined') {
      if (typeof enhancer !== 'function') {
        throw new Error('Expected the enhancer to be a function.');
      }
  
      return enhancer(createStore)(reducer, preloadedState);
    }
  
    if (typeof reducer !== 'function') {
      throw new Error('Expected the reducer to be a function.');
    }
  
    var currentReducer = reducer;
    var currentState = preloadedState;
    var currentListeners = [];
    var nextListeners = currentListeners;
    var isDispatching = false;
  
    function ensureCanMutateNextListeners() {
      if (nextListeners === currentListeners) {
        nextListeners = currentListeners.slice();
      }
    }
  
    /**
     * Reads the state tree managed by the store.
     *
     * @returns {any} The current state tree of your application.
     */
    function getState() {
      return currentState;
    }
  
    /**
     * Adds a change listener. It will be called any time an action is dispatched,
     * and some part of the state tree may potentially have changed. You may then
     * call `getState()` to read the current state tree inside the callback.
     *
     * You may call `dispatch()` from a change listener, with the following
     * caveats:
     *
     * 1. The subscriptions are snapshotted just before every `dispatch()` call.
     * If you subscribe or unsubscribe while the listeners are being invoked, this
     * will not have any effect on the `dispatch()` that is currently in progress.
     * However, the next `dispatch()` call, whether nested or not, will use a more
     * recent snapshot of the subscription list.
     *
     * 2. The listener should not expect to see all state changes, as the state
     * might have been updated multiple times during a nested `dispatch()` before
     * the listener is called. It is, however, guaranteed that all subscribers
     * registered before the `dispatch()` started will be called with the latest
     * state by the time it exits.
     *
     * @param {Function} listener A callback to be invoked on every dispatch.
     * @returns {Function} A function to remove this change listener.
     */
    function subscribe(listener) {
      if (typeof listener !== 'function') {
        throw new Error('Expected listener to be a function.');
      }
  
      var isSubscribed = true;
  
      ensureCanMutateNextListeners();
      nextListeners.push(listener);
  
      return function unsubscribe() {
        if (!isSubscribed) {
          return;
        }
  
        isSubscribed = false;
  
        ensureCanMutateNextListeners();
        var index = nextListeners.indexOf(listener);
        nextListeners.splice(index, 1);
      };
    }
  
    /**
     * Dispatches an action. It is the only way to trigger a state change.
     *
     * The `reducer` function, used to create the store, will be called with the
     * current state tree and the given `action`. Its return value will
     * be considered the **next** state of the tree, and the change listeners
     * will be notified.
     *
     * The base implementation only supports plain object actions. If you want to
     * dispatch a Promise, an Observable, a thunk, or something else, you need to
     * wrap your store creating function into the corresponding middleware. For
     * example, see the documentation for the `redux-thunk` package. Even the
     * middleware will eventually dispatch plain object actions using this method.
     *
     * @param {Object} action A plain object representing “what changed”. It is
     * a good idea to keep actions serializable so you can record and replay user
     * sessions, or use the time travelling `redux-devtools`. An action must have
     * a `type` property which may not be `undefined`. It is a good idea to use
     * string constants for action types.
     *
     * @returns {Object} For convenience, the same action object you dispatched.
     *
     * Note that, if you use a custom middleware, it may wrap `dispatch()` to
     * return something else (for example, a Promise you can await).
     */
    function dispatch(action) {
      if (!isPlainObject(action)) {
        throw new Error('Actions must be plain objects. ' + 'Use custom middleware for async actions.');
      }
  
      if (typeof action.type === 'undefined') {
        throw new Error('Actions may not have an undefined "type" property. ' + 'Have you misspelled a constant?');
      }
  
      if (isDispatching) {
        throw new Error('Reducers may not dispatch actions.');
      }
  
      try {
        isDispatching = true;
        currentState = currentReducer(currentState, action);
      } finally {
        isDispatching = false;
      }
  
      var listeners = currentListeners = nextListeners;
      for (var i = 0; i < listeners.length; i++) {
        listeners[i]();
      }
  
      return action;
    }
  
    /**
     * Replaces the reducer currently used by the store to calculate the state.
     *
     * You might need this if your app implements code splitting and you want to
     * load some of the reducers dynamically. You might also need this if you
     * implement a hot reloading mechanism for Redux.
     *
     * @param {Function} nextReducer The reducer for the store to use instead.
     * @returns {void}
     */
    function replaceReducer(nextReducer) {
      if (typeof nextReducer !== 'function') {
        throw new Error('Expected the nextReducer to be a function.');
      }
  
      currentReducer = nextReducer;
      dispatch({ type: ActionTypes.INIT });
    }
  
    /**
     * Interoperability point for observable/reactive libraries.
     * @returns {observable} A minimal observable of state changes.
     * For more information, see the observable proposal:
     * https://github.com/zenparsing/es-observable
     */
    function observable() {
      var _ref;
  
      var outerSubscribe = subscribe;
      return _ref = {
        /**
         * The minimal observable subscription method.
         * @param {Object} observer Any object that can be used as an observer.
         * The observer object should have a `next` method.
         * @returns {subscription} An object with an `unsubscribe` method that can
         * be used to unsubscribe the observable from the store, and prevent further
         * emission of values from the observable.
         */
        subscribe: function subscribe(observer) {
          if (typeof observer !== 'object') {
            throw new TypeError('Expected the observer to be an object.');
          }
  
          function observeState() {
            if (observer.next) {
              observer.next(getState());
            }
          }
  
          observeState();
          var unsubscribe = outerSubscribe(observeState);
          return { unsubscribe: unsubscribe };
        }
      }, _ref[$$observable] = function () {
        return this;
      }, _ref;
    }
  
    // When a store is created, an "INIT" action is dispatched so that every
    // reducer returns their initial state. This effectively populates
    // the initial state tree.
    dispatch({ type: ActionTypes.INIT });
  
    return _ref2 = {
      dispatch: dispatch,
      subscribe: subscribe,
      getState: getState,
      replaceReducer: replaceReducer
    }, _ref2[$$observable] = observable, _ref2;
  }