title: Map object has no len() in Python 3
body: <p>I have this Python tool written by someone else to flash a certain microcontroller, but he has written this tool for Python 2.6 and I am using Python 3.3.</p>
  
  <p>So, most of it I got ported, but this line is making problems:</p>
  
  <pre class="lang-py prettyprint-override"><code>data = map(lambda c: ord(c), file(args[0], 'rb').read()) 
  </code></pre>
  
  <p>The <code>file</code> function does not exist in Python 3 and has to be replaced with <code>open</code>. But then, a function which gets <code>data</code> as an argument causes an exception: </p>
  
  <pre><code>TypeError: object of type 'map' has no len()
  </code></pre>
  
  <p>But what I see so far in the documentation is, that <code>map</code> has to join iterable types to one big iterable, am I missing something?</p>
  
  <p>What do I have to do to port this to Python 3?</p>