const (
	// minimum and maximum runes involved in folding.
	// checked during test.
	minFold = 0x0041
	maxFold = 0x1e943
)

// appendFoldedRange returns the result of appending the range lo-hi
// and its case folding-equivalent runes to the class r.
func appendFoldedRange(r []rune, lo, hi rune) []rune {
	// Optimizations.
	if lo <= minFold && hi >= maxFold {
		// Range is full: folding can't add more.