code: func (l VirtualDeviceList) PrimaryMacAddress() string {
  	eth0 := l.Find("ethernet-0")
  
  	if eth0 == nil {
  		return ""
  	}
  
  	return eth0.(types.BaseVirtualEthernetCard).GetVirtualEthernetCard().MacAddress
  }
docs: // PrimaryMacAddress returns the MacAddress field of the primary VirtualEthernetCard