func isValidRecordText(text []byte) bool {
	var last rune
	for i := 0; i < len(text); {
		r, size := utf8.DecodeRune(text[i:])
		if r < 0x20 && r != '\n' || r == utf8.RuneError && size == 1 || last == '\n' && r == '\n' {
			return false
		}
		i += size
		last = r
	}
	if last != '\n' {
		return false
	}
	return true
}

	}
	buf = append(buf, quote)
	for width := 0; len(s) > 0; s = s[width:] {
		r := rune(s[0])
		width = 1
		if r >= utf8.RuneSelf {
			r, width = utf8.DecodeRuneInString(s)
		}
		if width == 1 && r == utf8.RuneError {
			buf = append(buf, `\x`...)
			buf = append(buf, lowerhex[s[0]>>4])
			buf = append(buf, lowerhex[s[0]&0xF])
			continue
		}
		buf = appendEscapedRune(buf, r, quote, ASCIIonly, graphicOnly)
	}

)

// bytesToKey tries to parse a key sequence from b. If successful, it returns
// the key and the remainder of the input. Otherwise it returns utf8.RuneError.
func bytesToKey(b []byte, pasteActive bool) (rune, []byte) {
	if len(b) == 0 {
		return utf8.RuneError, nil
	}

	if !pasteActive {
		switch b[0] {
		case 1: // ^A
			return keyHome, b[1:]
		case 2: // ^B
			return keyLeft, b[1:]

}

func ExampleEncodeRune_outOfRange() {
	runes := []rune{
		// Less than 0, out of range.
		-1,
		// Greater than 0x10FFFF, out of range.
		0x110000,
		// The Unicode replacement character.
		utf8.RuneError,
	}
	for i, c := range runes {
		buf := make([]byte, 3)
		size := utf8.EncodeRune(buf, c)
		fmt.Printf("%d: %d %[2]s %d\n", i, buf, size)
	}
	// Output:
	// 0: [239 191 189] � 3

			if b != '\\' && (b == ' ' || b == '=' || !safeSet[b]) {
				return true
			}
			i++
			continue
		}
		r, size := utf8.DecodeRuneInString(s[i:])
		if r == utf8.RuneError || unicode.IsSpace(r) || !unicode.IsPrint(r) {
			return true
		}
		i += size
	}
	return false

		return
	}
	if chunk[0] == '\\' {
		chunk = chunk[1:]
		if len(chunk) == 0 {
			err = ErrBadPattern
			return
		}
	}
	r, n := utf8.DecodeRuneInString(chunk)
	if r == utf8.RuneError && n == 1 {
		err = ErrBadPattern
	}
	nchunk = chunk[n:]
	if len(nchunk) == 0 {
		err = ErrBadPattern
	}
	return

				dst.WriteString(`u00`)
				dst.WriteByte(hexTable[b>>4])
				dst.WriteByte(hexTable[b&0xF])
			}
			i++
			start = i
			continue
		}
		c, size := utf8.DecodeRuneInString(s[i:])
		if c == utf8.RuneError && size == 1 {
			if start < i {
				dst.WriteString(s[start:i])
			}
			dst.WriteString(`\ufffd`)
			i += size
			start = i
			continue
		}
		// U+2028 is LINE SEPARATOR.

		got := exactly16Bytes(str)
		if len(got) != 16 {
			t.Errorf("exactly16Bytes(%q) is %q, length %d", str, got, len(got))
		}
		// Make sure it is full runes.
		for _, c := range got {
			if c == utf8.RuneError {
				t.Errorf("exactly16Bytes(%q) is %q, has partial rune", str, got)
			}
		}
	}

Loop:
	for {
		r, size := utf8.DecodeRuneInString(p.s[i:])

		switch {
		case size == 0:
			return "", errors.New("mail: unclosed quoted-string")

		case size == 1 && r == utf8.RuneError:
			return "", fmt.Errorf("mail: invalid utf-8 in quoted-string: %q", p.s)

		case escaped:
			//  quoted-pair = ("\" (VCHAR / WSP))

			if !isVchar(r) && !isWSP(r) {

			t.Errorf("%s: panicked = %v; want %v", tt.name, got, tt.wantPanic)
		}
	}
}

func TestBuilderWriteInvalidRune(t *testing.T) {
	// Invalid runes, including negative ones, should be written as
	// utf8.RuneError.
	for _, r := range []rune{-1, utf8.MaxRune + 1} {
		var b Builder
		b.WriteRune(r)
		check(t, &b, "\uFFFD")
	}
}

var someBytes = []byte("some bytes sdljlk jsklj3lkjlk djlkjw")