func (s *snippet) ID() string {
    h := sha256.New()
    h.Write(s.Body)
    sum := h.Sum(nil)

    b := make([]byte, base64.URLEncoding.EncodedLen(len(sum)))
    base64.URLEncoding.Encode(b, sum)

    hashLen := 11
    return string(b)[:hashLen]
}