title: Where is the 'do' operator on rxjs 6?
body: <p>We are slowly updagrading from angular 4 to 5 then 6. So we upgraded rxjs. I used to do</p>
  
  <pre><code>Observable.of(test').do(i=&gt;console.log(i))
  </code></pre>
  
  <p>In the new rxjs, I can't find the do operator something like: </p>
  
  <pre><code>of('test')
  .pipe(do(i=&gt;console.log(i)
  )
  </code></pre>
  
  <p>What's the proper way ?</p>