title: Add prefix to dataframe columns that match those names in a list
body: <p>Consider that I have a list called columns_to_prefix.</p>
  <p>The list looks like this:</p>
  <p>columns_to_prefix = ['fruit', 'colour', 'country']</p>
  <p>Then consider that I had a dataframe as follows:</p>
  <pre><code>fruit    colour    popularity    country   cost
  Apple    Green     High          UK        2
  Berry    Red       High          Spain     4
  </code></pre>
  <p>I want to put the prefix of 'the_' in front of the columns in this list.</p>
  <p>data = data['columns_to_prefix'].add_prefix('the_')</p>
  <p>This is an example dataframe, my actual dataframe has hundreds of columns so a method that uses the specific column names will not work.</p>