title: rxjs v6 / redux-observable v1.0.0: Operators not working in epic
body: <p>I am using the latest version of redux-observable and Rxjs i.e</p>
  
  <pre><code>// My version
  "redux-observable": "^1.0.0",
  "rxjs": "^6.3.2"
  </code></pre>
  
  <p>The store - middleware, setup looks like this: </p>
  
  <pre><code>// Setting up middlewares
  import { pingEpic } from './epics';
  import pingReducer from './reducers/pingReducer';
  
  import { combineReducers, createStore, applyMiddleware } from 'redux';
  import { combineEpics, createEpicMiddleware } from 'redux-observable';
  
  const rootReducer = combineReducers(pingReducer);
  const rootEpic = combineEpics(pingEpic);
  
  const epicMiddleware = createEpicMiddleware();
  
  const store = createStore(rootReducer,
      applyMiddleware(epicMiddleware)
  );
  
  epicMiddleware.run(rootEpic);
  export default store;
  </code></pre>
  
  <p>And my epic looks like this</p>
  
  <pre><code>// pingEpic.js
  import { mapTo } from 'rxjs/operator/mapTo';
  import { ofType } from 'redux-observable';
  export const pingEpic = action$ =&gt; action$.pipe(
      ofType('PING'),
      mapTo({ type: 'PONG' })
  );
  </code></pre>
  
  <p>So when I executed the program for the first time I got the following error:</p>
  
  <p><a href="https://i.stack.imgur.com/t7UuS.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/t7UuS.png" alt="enter image description here"></a></p>
  
  <p>I googled it and <a href="https://github.com/MurhafSousli/ngx-progressbar/issues/112#issuecomment-388332618" rel="nofollow noreferrer">found a solution here</a> which says to install <code>rxjs-compat@6</code> (however it doesn't makes any sense) I installed that too! And then I ran into the following error:</p>
  
  <p><a href="https://i.stack.imgur.com/8urBG.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/8urBG.png" alt="enter image description here"></a>.</p>
  
  <p>I don't know what/where am I doing wrong? Any help would be much appreciated!</p>
  
  <p>Thanks</p>