code: def windowed_iter(src, size):
      """Returns tuples with length *size* which represent a sliding
      window over iterable *src*.
      >>> list(windowed_iter(range(7), 3))
      [(0, 1, 2), (1, 2, 3), (2, 3, 4), (3, 4, 5), (4, 5, 6)]
  
      If the iterable is too short to make a window of length *size*,
      then no window tuples are returned.
      >>> list(windowed_iter(range(3), 5))
      []
      """
      # TODO: lists? (for consistency)
      tees = itertools.tee(src, size)
      try:
          for i, t in enumerate(tees):
              for _ in xrange(i):
                  next(t)
      except StopIteration:
          return izip([])
      return izip(*tees)
  
imports: import os
  import math
  import time
  import codecs
  import random
  import socket
  import hashlib
  import itertools
  from collections import Mapping, Sequence, Set, ItemsView
label_desc: Use image node_id 11 for calling a global function with example usage: windowed_iter(src, size) and returns: izip, izip