title: How to fill area under step curve using pyplot?
body: <p>I have plotted two step curves using <code>pyplot.step()</code>, and I would like to shade in the area beneath these curves (ideally with transparent shading). <code>pyplot.fill_between()</code> assumes linear interpolation, whereas I want to see step interpolation, as displayed below:<a href="https://i.stack.imgur.com/H6J63.png" rel="noreferrer"><img src="https://i.stack.imgur.com/H6J63.png" alt="step curves without shading"></a></p>
  
  <p>How can I shade in the region beneath these curves? Transparent coloring would be great, as this would make clear where these curves overlap.</p>