cmp/report_slices.go
func formatASCII(s string) string {
	b := bytes.Repeat([]byte{'.'}, len(s))
	for i := 0; i < len(s); i++ {
		if ' ' <= s[i] && s[i] <= '~' {
			b[i] = s[i]
		}
	}
	return string(b)
}
func formatASCII(s string) string {
	b := bytes.Repeat([]byte{'.'}, len(s))
	for i := 0; i < len(s); i++ {
		if ' ' <= s[i] && s[i] <= '~' {
			b[i] = s[i]
		}
	}
	return string(b)
}
// formatASCII formats s as an ASCII string.
// This is useful for printing binary strings in a semi-legible way.