anchor.diff:      dhcpConfig = mkOption {
         default = {};
         example = { UseDNS = true; UseRoutes = true; };
  -      type = types.attrsOf unitOption;
  +      type = types.addCheck (types.attrsOf unitOption) checkDhcp;
         description = ''
           Each attribute in this set specifies an option in the
           <literal>[DHCP]</literal> section of the unit.  See
  
positive.code:     tapConfig = mkOption {
        default = {};
        example = { User = "openvpn"; };
        type = types.attrsOf unitOption;
        description = ''
          Each attribute in this set specifies an option in the
          <literal>[Tap]</literal> section of the unit.  See
  
negative.code:     netdevConfig = mkOption {
        default = {};
        example = { Name = "mybridge"; Kind = "bridge"; };
        type = types.addCheck (types.attrsOf unitOption) checkNetdev;
        description = ''
          Each attribute in this set specifies an option in the
          <literal>[Netdev]</literal> section of the unit.  See
  