results:   []string{"c1", "c2", "c3", "c5", "c4"},
		},
		{
			callbacks: []callback{{h: c1}, {h: c2, before: "c4", after: "c5"}, {h: c3}, {h: c4}, {h: c5}},
			results:   []string{"c1", "c5", "c2", "c3", "c4"},
		},
		{
			callbacks: []callback{{h: c1, after: "c3"}, {h: c2, before: "c4", after: "c5"}, {h: c3, before: "c5"}, {h: c4}, {h: c5}},
			results:   []string{"c3", "c1", "c5", "c2", "c4"},