Matplotlib cumulative plot
<p>What matplotlib function I should use for creating such "above" plots?</p>

<p>I've tried to find it in <a href="http://matplotlib.org/gallery.html" rel="nofollow noreferrer">gallery</a>, but I've not managed to do it.</p>

<p><a href="https://i.stack.imgur.com/fUThW.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/fUThW.png" alt="enter image description here"></a></p>