def METHOD_NAME(self):
    ts1 = toggle_set(['one', 'two', 'three'])
    ts2 = toggle_set(['four', '~~', 'five'])
    ts3 = toggle_set(['six', 'seven', '~three'])
    ts4 = ts1.merge_with(ts2).merge_with(ts3)
    assert_equal(ts4, toggle_set(['four', 'five', 'six', 'seven', '~three', '~~']))
    ts5 = ts2.merge_into(ts3).merge_into(ts1)
    assert_equal(ts5, toggle_set(['four', 'five', '~~']))
    ts6 = ts2.merge_into(ts3).merge_with(ts1)
    assert_equal(ts6, toggle_set(['one', 'two', 'three', 'four', 'five', '~~']))