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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 duplicates_removed(it, already_seen=()):
 """ Returns a list with duplicates removed from the iterable `it`. Order is preserved. """

    lst = []
    seen = set()
    for i in it:
        if i in seen or i in already_seen:
            continue
        lst.append(i)
        seen.add(i)
    return lst