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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 unflatten(guide, falttened_input):
 """Unflatten a falttened generator. Args: guide: A guide list to follow the structure falttened_input: A flattened iterator object Usage: guide = [["a"], ["b","c","d"], [["e"]], ["f"]] input_list = [0, 1, 2, 3, 4, 5, 6, 7] unflatten(guide, iter(input_list)) >> [[0], [1, 2, 3], [[4]], [5]] """

    return [unflatten(sub_list, falttened_input) if isinstance(sub_list, list)
            else next(falttened_input) for sub_list in guide]