title: Trying to change the index column of a Pandas Series?
body: <p>I have a Pandas Series, it looks like this when I output it to a CSV-</p>
  
  <pre><code>a_x,8
  b_x,14
  c_x,18
  d_x,26
  e_x,32
  </code></pre>
  
  <p>Here is the result I am trying to achieve-</p>
  
  <pre><code>a_bar,8
  b_bar,14
  c_bar,18
  d_bar,26
  e_bar,32
  </code></pre>
  
  <p>Seems like a simple operation but just can't get the result yet.
  Thank you.</p>