title: Iterate over a python sequence in multiples of n?
body: <p>How do I process the elements of a sequence in batches, idiomatically?</p>
  
  <p>For example, with the sequence "abcdef" and a batch size of 2, I would like to do something like the following:</p>
  
  <pre><code>for x, y in "abcdef":
      print "%s%s\n" % (x, y)
  ab
  cd
  ef
  </code></pre>
  
  <p>Of course, this doesn't work because it is expecting a single element from the list which itself contains 2 elements.</p>
  
  <p>What is a nice, short, clean, pythonic way to process the next n elements of a list in a batch, or sub-strings of length n from a larger string (two similar problems)?</p>