title: deprecated concat operator in RxJS epic
body: <p>I have an epic works well with concat operator. Webstorm starts saying it is deprecated in the way I use it. Says </p>
  
  <blockquote>
    <p>deprecated export function concat&lt;{type: string}[]>(     v1: {type: string}[],     scheduler: SchedulerLike): Observable>
    Use scheduled and concatAll (e.g. scheduled([o1, o2, o3], scheduler).pipe(concatAll())</p>
  </blockquote>
  
  <p>Can't figure out, how to rewrite this code?</p>
  
  <pre><code>const epic = action$ =&gt; action$.pipe(
    ofType(TYPE),
    mergeMap(() =&gt;
      concat(
        of({type: 'START'}),
        ajax.getJSON('someurl').pipe(
          mergeMap(serverResponse =&gt; ([
            {type: 'LOADED'},
            {type: 'DO_JOB', serverResponse}
          ]))
      )
    )
  )
  </code></pre>