       >>> pred = lambda x: x == 0
        >>> substitutes = [None]
        >>> list(replace(iterable, pred, substitutes, count=2))
        [1, 1, None, 1, 1, None, 1, 1, 0]

    Use *window_size* to control the number of items passed as arguments to
    *pred*. This allows for locating and replacing subsequences.

        >>> iterable = [0, 1, 2, 5, 0, 1, 2, 5]
        >>> window_size = 3
        >>> pred = lambda *args: args == (0, 1, 2)  # 3 items passed to pred
        >>> substitutes = [3, 4] # Splice in these items
        >>> list(replace(iterable, pred, substitutes, window_size=window_size))
        [3, 4, 5, 3, 4, 5]

    r-