4 x := append(arg) // want `x = append\(y\) is equivalent to x = y`
8 arg = append(arg) // want `x = append\(y\) is equivalent to x = y`
9 arg = append(arg, 1, 2, 3)
11 arg = append(arg, nilly...)
12 arg = append(arg, arg...)
14 append := func([]int) []int { return nil }