title: Renaming column names in Pandas
body: <p>I want to change the column labels of a Pandas DataFrame from</p>
  <pre><code>['$a', '$b', '$c', '$d', '$e']
  </code></pre>
  <p>to</p>
  <pre><code>['a', 'b', 'c', 'd', 'e']
  </code></pre>