code: func MakeRandomToken(c context.Context, l uint32) []byte {
  	rtok := make([]byte, l)
  	if _, err := cryptorand.Read(c, rtok); err != nil {
  		panic(err)
  	}
  	return rtok
  }
docs: // MakeRandomToken creates a cryptographically random byte slice of the
  // specified length. It panics if the specified length cannot be read in full.