title: Matplotlib legend for an arrow
body: <p>I would like to know how it is possible to label an <code>arrow</code> and show it in the legend of a plot.</p>
  
  <p>For instance if I do this</p>
  
  <pre><code> arrow(0,1,'dummy',label='My label')
  
   legend()
  </code></pre>
  
  <p>I do not see anything in the legend. I would like to see in the legend box an arrow next to its label.</p>