text: import Rx from 'rxjs';
  
  export default function configureStore(reducer$, initialState = {}) {
    return Rx.Observable.of(initialState)
            .merge(reducer$)
            .scan((state, reducer) => {
              return Object.assign({}, state, reducer(state))
            })
            .publishReplay(1)
            .refCount();
  }
  
  