title: How can i add a column to an existing Excel File using pandas?
body: <p>I have in my file a bunch of names and adresses and I want to add a column named Barcode on an it which i want to fill with the function generateBareCode()
  here is my code : </p>
  
  <pre><code>import uuid 
  import pandas as pd
  def generateBarCode(length):
      return str(uuid.uuid4()).replace('-','')[0:length]
  </code></pre>
  
  <p>thank you</p>