title: dispatch multiple actions in one effect
body: <p>I would like to dispatch two actions in one effect.
  Currently I have to declare two effects to achieve this :</p>
  <pre class="lang-ts prettyprint-override"><code>// first effect
  @Effect()
  action1$ = this.actions$
    .ofType(CoreActionTypes.MY_ACTION)
    .map(res =&gt; {
      return { type: &quot;ACTION_ONE&quot;}
    })
    .catch(() =&gt; Observable.of({
      type: CoreActionTypes.MY_ACTION_FAILED
    }));
  
  // second effect
  @Effect()
  action2$ = this.actions$
    .ofType(CoreActionTypes.MY_ACTION)
    .map(res =&gt; {
      return { type: &quot;ACTION_TWO&quot;}
    })
    .catch(() =&gt; Observable.of({
      type: CoreActionTypes.MY_ACTION_FAILED
    }));
  </code></pre>
  <p>Is it possible to have one action, be the source of two actions via a single effect?</p>