title: create new pandas column starting at 0
body: <p>I have created a new column in pandas called 'index', which incrementally adds a number for each row. </p>
  
  <pre><code>idx = 0
  df.insert(idx, 'index', value=range(1,len(df)+ 1))
  </code></pre>
  
  <p>However, my index currently starts at 1 and I would like to change it to start at 0. </p>
  
  <p>Current Output: </p>
  
  <pre><code>'index'
      1
      2
      3
      4
      5
    ...
  </code></pre>
  
  <p>How would I do this? </p>