code: func (n *Node) ValidateComplete() error {
  	if n.Incomplete() {
  		return errors.New("incomplete node")
  	}
  	if n.UDP() == 0 {
  		return errors.New("missing UDP port")
  	}
  	ip := n.IP()
  	if ip.IsMulticast() || ip.IsUnspecified() {
  		return errors.New("invalid IP (multicast/unspecified)")
  	}
  	// Validate the node key (on curve, etc.).
  	var key Secp256k1
  	return n.Load(&key)
  }
docs: // checks whether n is a valid complete node.