title: Append to List while Iterating
body: <p>I need this behavior, but would rather have a diminishing list rather than a growing one.
  Sequence order is important for this operation.</p>
  
  <pre><code>for item in mylist:
      if is_item_mature(item):
          ## Process him
      else:
          ## Check again later
          mylist.append(item)
  </code></pre>
  
  <p>but I would rather have it more like this. Does this behave like I think? Any better ways?</p>
  
  <pre><code>while mylist:
      item = list.pop(0)
      if is_item_mature(item):
          ##Process
      else:
          mylist.append(item)
  </code></pre>