anchor.diff:  
     checkDhcpV6 = checkUnitConfig "DHCPv6" [
       (assertOnlyFields [
  -      "UseDNS" "UseNTP" "RapidCommit" "ForceDHCPv6PDOtherInformation"
  +      "UseDNS"
  +      "UseNTP"
  +      "RapidCommit"
  +      "ForceDHCPv6PDOtherInformation"
         "PrefixDelegationHint"
       ])
       (assertValueOneOf "UseDNS" boolValues)
  
positive.code:   # refrain ourselves from providing a footgun.
    checkWireGuardPeer = checkUnitConfig "WireGuardPeer" [
      (assertOnlyFields [
        "PublicKey" "PresharedKeyFile" "AllowedIPs"
        "Endpoint" "PersistentKeepalive"
      ])
      (assertRange "PersistentKeepalive" 1 65535)
    ];
  
    checkVlan = checkUnitConfig "VLAN" [
      (assertOnlyFields ["Id" "GVRP" "MVRP" "LooseBinding" "ReorderHeader"])
      (assertRange "Id" 0 4094)
      (assertValueOneOf "GVRP" boolValues)
      (assertValueOneOf "MVRP" boolValues)
  
negative.code: 
    checkIpv6Prefix = checkUnitConfig "IPv6Prefix" [
      (assertOnlyFields [
        "AddressAutoconfiguration"
        "OnLink"
        "Prefix"
        "PreferredLifetimeSec"
        "ValidLifetimeSec"
      ])
      (assertValueOneOf "AddressAutoconfiguration" boolValues)
      (assertValueOneOf "OnLink" boolValues)
  