title: Python Plotly - add horizontal line to box plot
body: <p>I’m trying to add horizontal lines to the plot below at y=20 without success.</p>
  
  <p>Thanks for the help!</p>
  
  <pre><code>import plotly.express as px
  tips = px.data.tips()
  fig = px.box(tips, x="time", y="total_bill")
  fig.show()
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/GHAtr.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GHAtr.png" alt="enter image description here"></a></p>