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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 flatten_unique(l: Iterable) -> List: """ Return a list of UNIQUE non-list items in l """

    rval = OrderedDict()
    for e in l:
        if not isinstance(e, str) and isinstance(e, Iterable):
            for ev in flatten_unique(e):
                rval[ev] = None
        else:
            rval[e] = None
    return list(rval.keys())