title: Python lambda function
body: <p>What is happening here?</p>
  
  <pre><code>reduce(lambda x,y: x+y, [x for x in range(1,1000) if x % 3 == 0 or x % 5 == 0])
  </code></pre>
  
  <p>I understand how x is iterating through all of the numbers from 1 to 999 and taking out those that are divisible by 3 or 5, but the 'lambda x,y: x+y' part is stumping me.</p>