title: If a python iterator returns iterable objects, how can I chain those objects into one big iterator?
body: <p>I'll give a simplified example here. Suppose I have an iterator in python, and each object that this iterator returns is itself iterable. I want to take all the objects returned by this iterator and chain them together into one long iterator. Is there a standard utility to make this possible?</p>
  
  <p>Here is a contrived example. </p>
  
  <pre><code>x = iter([ xrange(0,5), xrange(5,10)])
  </code></pre>
  
  <p><code>x</code> is an iterator that returns iterators, and I want to chain all the iterators returned by x into one big iterator. The result of such an operation in this example should be 
  equivalent to xrange(0,10), and it should be lazily evaluated.</p>