<p>
The built-in functions do not have standard Go types,
so they can only appear in <a href="#Calls">call expressions</a>;
they cannot be used as function values.
</p>


<h3 id="Appending_and_copying_slices">Appending to and copying slices</h3>

<p>
The built-in functions <code>append</code> and <code>copy</code> assist in
common slice operations.

The memory model is specified more formally in the next section.
</p>

<p>
A data race is defined as
a write to a memory location happening concurrently with another read or write to that same location,
unless all the accesses involved are atomic data accesses as provided by the <code>sync/atomic</code> package.

	{"\xff-\xff", "-", -1, []string{"\xff", "\xff"}},
}

func TestSplit(t *testing.T) {
	for _, tt := range splittests {
		a := SplitN([]byte(tt.s), []byte(tt.sep), tt.n)

		// Appending to the results should not change future results.
		var x []byte
		for _, v := range a {
			x = append(v, 'z')
		}

		result := sliceOfString(a)
		if !eq(result, tt.a) {

		got.Reset()
		for i := 0; i < 1000; i++ {
			b := got.AvailableBuffer()
			b = strconv.AppendInt(b, int64(i), 10)
			got.Write(b)
		}
	})
	if n > 0 {
		t.Errorf("allocations occurred while appending")
	}
}

func TestRuneIO(t *testing.T) {
	const NRune = 1000
	// Built a test slice while we write the data
	b := make([]byte, utf8.UTFMax*NRune)
	var buf Buffer
	n := 0

create a map with initial space to hold <code>n</code> map elements.
The precise behavior is implementation-dependent.
</p>


<h3 id="Appending_and_copying_slices">Appending to and copying slices</h3>

<p>
The built-in functions <code>append</code> and <code>copy</code> assist in
common slice operations.