// Just return a copy.
		return append([]byte(nil), s[0]...)
	}

	var n int
	if len(sep) > 0 {
		if len(sep) >= maxInt/(len(s)-1) {
			panic("bytes: Join output length overflow")
		}
		n += len(sep) * (len(s) - 1)
	}
	for _, v := range s {
		if len(v) > maxInt-n {
			panic("bytes: Join output length overflow")
		}
		n += len(v)
	}

	b := bytealg.MakeNoZero(n)[:n:n]