def test_duplicates_removed_seq_types():
    # tuple
    x = util.duplicates_removed(('a', 'a', 'b'))
    assert ['a', 'b'] == x
    # list
    x = util.duplicates_removed(['a', 'a', 'b'])
    assert ['a', 'b'] == x
    # iterator
    x = util.duplicates_removed(iter(('a', 'a', 'b')))
    assert ['a', 'b'] == x 

def test_duplicates_removed_nonconsecutive():
    # keeps first
    x = util.duplicates_removed(('a', 'b', 'a'))
    assert ['a', 'b'] == x