w.Flush() // Don't forget to flush!
	// Output: Hello, world!
}

func ExampleWriter_AvailableBuffer() {
	w := bufio.NewWriter(os.Stdout)
	for _, i := range []int64{1, 2, 3, 4} {
		b := w.AvailableBuffer()
		b = strconv.AppendInt(b, i, 10)
		b = append(b, ' ')
		w.Write(b)
	}
	w.Flush()
	// Output: 1 2 3 4
}

// ExampleWriter_ReadFrom demonstrates how to use the ReadFrom method of Writer.

		empty(t, "TestWriteTo (2)", &b, s, make([]byte, len(testString)))
	}
}

func TestWriteAppend(t *testing.T) {
	var got Buffer
	var want []byte
	for i := 0; i < 1000; i++ {
		b := got.AvailableBuffer()
		b = strconv.AppendInt(b, int64(i), 10)
		want = strconv.AppendInt(want, int64(i), 10)
		got.Write(b)
	}
	if !Equal(got.Bytes(), want) {
		t.Fatalf("Bytes() = %q, want %q", &got, want)
	}

func (b *Buffer) Bytes() []byte { return b.buf[b.off:] }

// AvailableBuffer returns an empty buffer with b.Available() capacity.
// This buffer is intended to be appended to and
// passed to an immediately succeeding [Buffer.Write] call.
// The buffer is only valid until the next write operation on b.
func (b *Buffer) AvailableBuffer() []byte { return b.buf[len(b.buf):] }

func (b *Writer) Available() int { return len(b.buf) - b.n }

// AvailableBuffer returns an empty buffer with b.Available() capacity.
// This buffer is intended to be appended to and
// passed to an immediately succeeding [Writer.Write] call.
// The buffer is only valid until the next write operation on b.
func (b *Writer) AvailableBuffer() []byte {
	return b.buf[b.n:][:0]
}

	os.Stdout.Write(buf.Bytes())
	// Output: hello world
}

func ExampleBuffer_AvailableBuffer() {
	var buf bytes.Buffer
	for i := 0; i < 4; i++ {
		b := buf.AvailableBuffer()
		b = strconv.AppendInt(b, int64(i), 10)
		b = append(b, ' ')
		buf.Write(b)
	}
	os.Stdout.Write(buf.Bytes())
	// Output: 0 1 2 3
}

func ExampleBuffer_Cap() {

	got := new(bytes.Buffer)
	var want []byte
	rn := rand.New(rand.NewSource(0))
	w := NewWriterSize(got, 64)
	for i := 0; i < 100; i++ {
		// Obtain a buffer to append to.
		b := w.AvailableBuffer()
		if w.Available() != cap(b) {
			t.Fatalf("Available() = %v, want %v", w.Available(), cap(b))
		}

		// While not recommended, it is valid to append to a shifted buffer.