title: How can I, in python, iterate over multiple 2d lists at once, cleanly?
body: <p>If I'm making a simple grid based game, for example, I might have a few 2d lists. One might be for terrain, another might be for objects, etc. Unfortunately, when I need to iterate over the lists and have the contents of a square in one list affect part of another list, I have to do something like this.</p>
  
  <pre><code>for i in range(len(alist)):
      for j in range(len(alist[i])):
          if alist[i][j].isWhatever:
              blist[i][j].doSomething()
  </code></pre>
  
  <p>Is there a nicer way to do something like this?</p>