def unique_iterator(seq):
    """
    Returns an iterator containing all non-duplicate elements
    in the input sequence.
    """
    seen = set()
    for item in seq:
        if item not in seen:
            seen.add(item)
            yield item
def unique_iterator ( seq ) : seen = set ( ) for item in seq : if item not in seen : seen . add ( item ) yield item
Returns an iterator containing all non-duplicate elements
    in the input sequence.