title: How to add a reference line to the pyplot line chart ?
body: <p>I have a dataframe for which I have drawn a line chart and added a reference number using the below code </p>
  
  <pre><code>plt.figure(figsize=(15,5))
  plt.title('Parento Analysis',fontsize=20, color = 'blue')
  plt.xlabel('Product', fontsize=14)
  plt.ylabel('Sales Quantity', fontsize=14)
  plt.plot(parento['Cum_Product%'], parento['Cum_Sales%'],linewidth=3.0)
  plt.plot([10, 10], [0, 80], 'k-', lw=1,dashes=[2, 2])
  plt.plot([0, 10], [80, 80], 'k-', lw=1,dashes=[2, 2])
  plt.show()
  </code></pre>
  
  <p><a href="https://i.stack.imgur.com/7SmsX.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/7SmsX.png" alt="enter image description here"></a></p>
  
  <p>My solution seems a bit long for me.
  Is there any other short way with which I can draw the reference line for (10,80)?</p>