title: custom vertical line based on user input during run time
body: <p>Currently i add v line as follow: </p>
  
  <pre><code>axvline(y= uservalue, linewidth=1, linestyle=':', color='orangered') 
  </code></pre>
  
  <p>after drawing a plot, during the runtime,  is there way to get the uservalue and update the line position?  Basically i want to get the user input during the run time and update the plot accordingly. </p>