title: Matplotlib - add titles to the legend rows
body: <p>I created a legend which contains two rows, as below:</p>
  
  <p><a href="https://i.stack.imgur.com/DGOXb.png" rel="noreferrer"><img src="https://i.stack.imgur.com/DGOXb.png" alt="enter image description here"></a></p>
  
  <p>Is it possible to add a label/title to each row, that when I show the plot the legend appears as:</p>
  
  <pre><code>Title1: One One One
  Title2: Two Two Two
  </code></pre>
  
  <p>Many thanks for any suggestions!</p>