func isWS(b byte) bool {
	switch b {
	case '\t', '\n', '\x0c', '\r', ' ':
		return true
	}
	return false
}

// isTT reports whether the provided byte is a tag-terminating byte (0xTT)
// as defined in https://mimesniff.spec.whatwg.org/#terminology.
func isTT(b byte) bool {
	switch b {
	case ' ', '>':
		return true
	}
	return false
}

type sniffSig interface {