if 'A' <= sr && sr <= 'Z' && tr == sr+'a'-'A' {
				continue
			}
			return false
		}

		// General case. SimpleFold(x) returns the next equivalent rune > x
		// or wraps around to smaller values.
		r := unicode.SimpleFold(sr)
		for r != sr && r < tr {
			r = unicode.SimpleFold(r)
		}
		if r == tr {
			continue
		}
		return false
	}

	// One string is empty. Are both?

pkg unicode, func IsPunct(int32) bool
pkg unicode, func IsSpace(int32) bool
pkg unicode, func IsSymbol(int32) bool
pkg unicode, func IsTitle(int32) bool
pkg unicode, func IsUpper(int32) bool
pkg unicode, func SimpleFold(int32) int32
pkg unicode, func To(int, int32) int32
pkg unicode, func ToLower(int32) int32
pkg unicode, func ToTitle(int32) int32
pkg unicode, func ToUpper(int32) int32