title: How to add vertical lines to a histogram in plotly dash?
body: <p>I have a <code>graph</code> component that's is triggered upon a callback. Here's my code to plot a histogram from a callback function.</p>
  <pre><code>xtup = np.random.lognormal(90, 3, size=1000)
  xtup = list(map('{:.0f}'.format,xtup[0]))
  xarr = np.asarray(xtup).astype(np.float)
  
  data = [go.Histogram(
                       x = xarr,
                       nbinsx=50,
                       marker=dict(color=&quot;rgb(105,105,105)&quot;,
                                   opacity=0.5
                                  ),
  
         )]
  
  layout = {
              &quot;xaxis&quot;: {'title': 'Values',
                        'tickformat': '${:,.0f}'
                        #'range': [xarr.min(), xarr.max()]
                       },
              &quot;title&quot;: &quot;Distribution&quot;,
              &quot;width&quot;: 650,
              &quot;height&quot;: 400,
              &quot;autosize&quot;: True
  }
  
  return{'data':data, 'layout':layout}
  </code></pre>
  <p>I'd like to add a dashed vertical line at the mean of the distribution.</p>