title: Observables "retryWhen" delay
body: <p>How can I set a delay in <code>retryWhen</code>?</p>
  
  <pre><code>import 'rxjs/add/operator/retry';
  import 'rxjs/add/operator/retrywhen';
  </code></pre>
  
  <p>...</p>
  
  <pre><code>constructor(http: Http) {
  
    var headers = new Headers();
    headers.append('Content-Type', 'text/plain');
    http.post('https://mywebsite.azurewebsites.net/account/getip', "", { headers: headers })
       .retryWhen(errors =&gt; {
                  return errors.delay(1000);   // errors is not a function
                })
               (event) =&gt; {
                  // handle events
                  this.ip = event.json();
              },
              (error) =&gt; {
                  console.error(error);
                  toastr.error('No connection to server. Please reload the page!')
  
              }
              );
   }
  </code></pre>
  
  <p>I am getting the error: <code>errors is not a function</code>.</p>