code: def iterwindows(self, count=64, window_shape=(256, 256)):
          
          if count is None:
              while True:
                  yield self.randwindow(window_shape)
          else:
              for i in xrange(count):
                  yield self.randwindow(window_shape)
docs: Iterate over random windows of an image
  
          Args:
              count (int): the number of the windows to generate. Defaults to 64, if `None` will continue to iterate over random windows until stopped.
              window_shape (tuple): The desired shape of each image as (height, width) in pixels.
  
          Yields:
              image: an image of the given shape and same type.