const NRune = 1000
	byteBuf := new(bytes.Buffer)
	w := NewWriter(byteBuf)
	// Write the runes out using WriteRune
	buf := make([]byte, utf8.UTFMax)
	for r := rune(0); r < NRune; r++ {
		size := utf8.EncodeRune(buf, r)
		nbytes, err := w.WriteRune(r)
		if err != nil {
			t.Fatalf("WriteRune(0x%x) error: %s", r, err)
		}
		if nbytes != size {
			t.Fatalf("WriteRune(0x%x) expected %d, got %d", r, size, nbytes)
		}

			}
		}
		buf[n-1] = '\x00'
	}
}

func bmIndexRune(index func([]byte, rune) int) func(b *testing.B, n int) {
	return func(b *testing.B, n int) {
		buf := bmbuf[0:n]
		utf8.EncodeRune(buf[n-3:], '世')
		for i := 0; i < b.N; i++ {
			j := index(buf, '世')
			if j != n-3 {
				b.Fatal("bad index", j)
			}
		}
		buf[n-3] = '\x00'
		buf[n-2] = '\x00'
		buf[n-1] = '\x00'
	}
}