title: Converting Index into MultiIndex (hierarchical index) in Pandas
body: <p>In the data I am working with the index is compound - i.e. it has both item name and a timestamp, e.g. <code>name@domain.com|2013-05-07 05:52:51 +0200</code>.</p>
  
  <p>I want to do hierarchical indexing, so that the same e-mails are grouped together, so I need to convert a DataFrame Index into a MultiIndex (e.g. for the entry above - <code>(name@domain.com, 2013-05-07 05:52:51 +0200)</code>).</p>
  
  <p>What is the most convenient method to do so?</p>