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"},

0000310 2e 05 9c f4 aa 1e a8 cd a6 82 c7 59 0f 5e 9d e0
0000320 bb fc 6c d6 99 23 eb 36 ad c6 c5 e1 d8 e1 e2 3e
0000330 d9 90 5a f7 91 5d 6f bc 33 6d 98 47 d2 7c 2e 2f
0000340 99 a4 25 72 85 49 2c be 0b 5b af 8f e5 6e 81 a6
0000350 a3 5a 6f 39 53 3a ab 7a 8b 1e 26 f7 46 6c 7d 26
0000360 53 b3 22 31 94 d3 83 f2 18 4d f5 92 33 27 53 97
0000370 0f d3 e6 55 9c a6 c5 31 87 6f d3 f3 ae 39 6f 56
0000380 10 7b ab 7e d0 b4 ca f2 b8 05 be 3f 0e 6e 5a 75

	VMOVLPD X20, (SP)(AX*2)          // 62e1fd08132444 or 62e1fd28132444 or 62e1fd48132444
	// "VPEXTRW imm8u, xmm1, r32/m16"/15 vs "VPEXTRW imm8u, xmm2, r32"/C5.
	VPEXTRW $17, X20, AX              // 62b17d08c5c411 or 62e37d0815e011 or 62e3fd0815e011
	VPEXTRW $127, X20, AX             // 62b17d08c5c47f or 62e37d0815e07f or 62e3fd0815e07f

	c3 = len([10]float64{c1})        // [10]float64{c1} contains no function calls
	c4 = len([10]float64{imag(2i)})  // imag(2i) is a constant and no function call is issued
	c5 = len([10]float64{imag(z)})   // invalid: imag(z) is a (non-constant) function call
)
var z complex128
</pre>

<h3 id="Allocation">Allocation</h3>

<p>

	c3 = len([10]float64{c1})        // [10]float64{c1} contains no function calls
	c4 = len([10]float64{imag(2i)})  // imag(2i) is a constant and no function call is issued
	c5 = len([10]float64{imag(z)})   // invalid: imag(z) is a (non-constant) function call
)
var z complex128
</pre>


<h3 id="Making_slices_maps_and_channels">Making slices, maps and channels</h3>

<p>