title: Plotly: How to add vertical line to plotly plot?
body: <p>I am testing plotly express.</p>
  <p>I have the latest version: <code>0.4.1</code></p>
  <p>I am trying to plot the most basic chart in their tutorial but it's throwing an error:</p>
  <pre><code>import plotly.express as px
  
  df = px.data.iris()
  fig = px.scatter(df, x=&quot;petal_length&quot;, y=&quot;petal_width&quot;)
  fig.add_vline(x=2.5, line_width=3, line_dash=&quot;dash&quot;, line_color=&quot;green&quot;)
  fig.add_hrect(y0=0.9, y1=2.6, line_width=0, fillcolor=&quot;red&quot;, opacity=0.2)
  fig.show()
  
  
  AttributeError: 'Figure' object has no attribute 'add_vline'
  </code></pre>
  <p>Am I doing something wrong?</p>
  <p>All I want to do is to get <a href="https://plotly.com/python/horizontal-vertical-shapes/" rel="nofollow noreferrer"><code>add_vline</code></a> working.</p>
  <p>It's the second example on the how-to guide here: <a href="https://plotly.com/python/horizontal-vertical-shapes/" rel="nofollow noreferrer">https://plotly.com/python/horizontal-vertical-shapes/</a></p>