anchor.diff:                default = 1;
                 description = ''
                   The number of concurrent jobs the build machine supports. The
  -                build machine will enforce its own limits but this allows hydra
  +                build machine will enforce its own limits, but this allows hydra
                   to schedule better since there is no work-stealing between build
                   machines.
                 '';
  
positive.code:       };
  
        buildMachines = mkOption {
          type = types.loaOf (submodule ({ config }: {
            options = {
              sshUser = mkOption {
                type = types.nullOr types.string;
                default = null;
                description = ''
                  The user as who to SSH to the build machine.
                '';
              };
              hostName = mkOption {
                type = types.string;
                description = ''
                  The hostname of the build machine.
                '';
              };
              system = mkOption {
                type = types.string;
                default = null;
                description = ''
                  The system type the build machine can execute derivations on.
                  null if multiple are supported.
                '';
              };
              systems = mkOption {
                type = types.listOf types.string;
                default = [];
                description = ''
                  The system types the build machine can execute derivations on.
                '';
              };
              sshKey = mkOption {
                type = types.string;
                default = "-";
                description = ''
                  The path to the SSH private key with which to authenticate with
                  the build machine. <literal>"-"</literal> indicates falling back
                  on defaults.
                '';
              };
              maxJobs = mkOption {
  
negative.code:               type = types.int;
                default = 1;
                description = ''
                  The relative speed of this builder. This is an arbitrary integer
                  that indicates the speed of this builder, relative to other
                  builders. Higher is faster.
                '';
              };
              mandatoryFeatures = mkOption {
                type = types.listOf types.str;
                default = [];
                example = [ "big-parallel" ];
                description = ''
                  A list of features mandatory for this builder. The builder will
                  be ignored for derivations that don't require all features in
                  this list. All mandatory features are automatically included in
                  <varname>supportedFeatures</varname>.
                '';
              };
              supportedFeatures = mkOption {
                type = types.listOf types.str;
                default = [];
                example = [ "kvm" "big-parallel" ];
                description = ''
                  A list of features supported by this builder. The builder will
                  be ignored for derivations that require features not in this
                  list.
                '';
              };
            };
          }));
          default = [];
          description = ''
            This option lists the machines to be used if distributed builds are
            enabled (see <option>nix.distributedBuilds</option>).
            Nix will perform derivations on those machines via SSH by copying the
            inputs to the Nix store on the remote machine, starting the build,
            then copying the output back to the local Nix store.
          '';
        };
  
  