code: func (k SecretKey) Precompute(peer saltpack.BoxPublicKey) saltpack.BoxPrecomputedSharedKey {
  	var res PrecomputedSharedKey
  	box.Precompute((*[32]byte)(&res), (*[32]byte)(peer.ToRawBoxKeyPointer()), (*[32]byte)(&k.sec))
  	return res
  }
docs: // Precompute computes a shared key with the passed public key.