code: func GetRelayMessageOption(o dhcp6.Options) (RelayMessageOption, error) {
  	v, err := o.GetOne(dhcp6.OptionRelayMsg)
  	if err != nil {
  		return nil, err
  	}
  
  	var r RelayMessageOption
  	err = (&r).UnmarshalBinary(v)
  	return r, err
  }
docs: // GetRelayMessageOption returns the Relay Message Option value, as described
  // in RFC 3315, Section 22.10.
  //
  // The RelayMessage option carries a DHCP message in a Relay-forward or
  // Relay-reply message.