title: What does this anonymmous split function do?
body: <pre><code>narcoticsCrimeTuples = narcoticsCrimes.map(lambda x:(x.split(",")[0], x))
  </code></pre>
  
  <p>I have a CSV I am trying to parse by splitting on commas and the first entry in each array of strings is the primary key.<br>
  I would like to get the key on a separate line (or just separate) from the value when calling <code>narcoticsCrimeTuples.first()[1]</code></p>
  
  <p>My current understanding is 'split x by commas, take the first part of each split [0], and return that as the new x', but I'm pretty sure that middle part is not right because the number inside the [] can be anything and returns the same result.</p>