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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 pickle_sequence(objects):
 """ Convert an iterable of objects into a list of pickled objects. If the iterable contains copies, the pickling will be done only once. If the iterable contains objects already pickled, they will not be pickled again. :param objects: a sequence of objects to pickle """

    cache = {}
    out = []
    for obj in objects:
        obj_id = id(obj)
        if obj_id not in cache:
            if isinstance(obj, Pickled):  # already pickled
                cache[obj_id] = obj
            else:  # pickle the object
                cache[obj_id] = Pickled(obj)
        out.append(cache[obj_id])
    return out