title: regular expression for different forms of people's name representation
body: <p>I'm writing a python regular expression tries to capture people's names. </p>
  
  <p>They can be in the form <em><code>first_name last_name</code></em> or <em><code>last_name, first_name</code></em>. </p>
  
  <p>This is my regular expression for that:</p>
  
  <pre><code>(?P&lt;first&gt;\w+) (?P&lt;last&gt;\w+)|(?P&lt;last&gt;\w+), (?P&lt;first&gt;\w+)
  </code></pre>
  
  <p>However, it's causing a sub-pattern naming error. Is there a way to fix it? </p>