code: func (pssapi *API) SetPeerPublicKey(pubkey hexutil.Bytes, topic Topic, addr PssAddress) error {
  	pk, err := crypto.UnmarshalPubkey(pubkey)
  	if err != nil {
  		return fmt.Errorf("Cannot unmarshal pubkey: %x", pubkey)
  	}
  	err = pssapi.Pss.SetPeerPublicKey(pk, topic, addr)
  	if err != nil {
  		return fmt.Errorf("Invalid key: %x", pk)
  	}
  	return nil
  }
docs: // Set Public key to associate with a particular Pss peer