def test_iadd(self, evt):
        rval = event.ReturnValue(append_events=[evt])
        rval2 = event.ReturnValue(eat=True, append_events=[evt])
        rset = event.ResultSet()

        rset += rval
        rset += rval2
        rset += None
        assert rset.eat
        assert rset.append_events == [evt, evt]
def test_either():
    """Either f or g."""
    p = are.above(3) | are.below(2)
    ps = [p(x) for x in range(1, 6)]
    assert ps == [True, False, False, True, True]