title: Ploting an x-y graph with "four" axes
body: <p>Generally, I'm trying to understand whether <em>matplotlib</em> actually has this capability. </p>
  
  <p>I have a <strong><em>speed</em></strong> (on x axis) in mph vs.  <strong><em>power</em></strong> (on y axis) in kW graph, to which I need to add a <strong><em>rotations</em></strong> (on second y axis, <strong>to the right</strong>) and another <strong><em>speed</em></strong> (on second x axis, <strong>up on the top</strong>) in km/h.</p>
  
  <p>Power in kW is in correlation with speed in mph, while rotations is in correlation with Power, and second speed (on second x axis) is just the first speed multiplied with a convertion coefficient.</p>
  
  <p><em><strong>So, my question is - how can I plot a x-y plot in matplotlib with two x and two y axis?</em></strong></p>