title: Encoding a numeric string into a shortened alphanumeric string, and back again
body: <p>Quick question. I'm trying to find or write an encoder in Python to shorten a string of numbers by using upper and lower case letters. The numeric strings look something like this:</p>
  
  <pre class="lang-none prettyprint-override"><code>20120425161608678259146181504021022591461815040210220120425161608667
  </code></pre>
  
  <p>The length is always the same. </p>
  
  <p>My initial thought was to write some simple encoder to utilize upper and lower case letters and numbers to shorten this string into something that looks more like this: </p>
  
  <pre class="lang-none prettyprint-override"><code>a26Dkd38JK
  </code></pre>
  
  <p>That was completely arbitrary, just trying to be as clear as possible. 
  I'm certain that there is a really slick way to do this, probably already built in. Maybe this is an embarrassing question to even be asking.</p>
  
  <p>Also, I need to be able to take the shortened string and convert it back to the longer numeric value.
  Should I write something and post the code, or is this a one line built in function of Python that I should already know about? </p>
  
  <p>Thanks!</p>