title: Python progressbar does not display
body: <p>I've got this function that takes some time to complete and I'd like to display the current progress per element in the list.</p>
  
  <p>This is how it's coded:</p>
  
  <pre><code>import progressbar
  
  def func(self):
      bar = progressbar.ProgressBar(
          maxval=len(some_list),
          widgets=[progressbar.Bar('=', '[', ']'), ' ', progressbar.Percentage()]
      )
      progress = 0
      bar.start()
      for r in some_list:
          #heavy calculation
          progress += 1
          bar.update(progress)
      bar.finish()
  </code></pre>
  
  <p>Yet when I run, the progressbar isn't displayed (nothing in fact is), the function just does its thing and when the function ends 20 seconds later I suddenly get the full bar in the console </p>
  
  <p><img src="https://i.stack.imgur.com/JL897.png" alt=""></p>
  
  <p>What am I doing wrong?</p>
  
  <p>I'm using Kubuntu latest version with python 3.7.4 and PyCharm.</p>