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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def ffill(iterable):
 """Forward fill non None values in some iterable. Parameters iterable : iterable The iterable to forward fill. Yields ------ e : any The last non None value or None if there has not been a non None value. """

    it = iter(iterable)
    previous = next(it)
    yield previous
    for e in it:
        if e is None:
            yield previous
        else:
            previous = e
            yield e