anchor.diff:  
       deployment.adhoc.createVMCommand = mkOption {
         default = "create-vm";
  +      type = types.uniq types.string;
         description = ''
           Remote command to create a NixOS virtual machine.  It should
           print an identifier denoting the VM on standard output.
  
positive.code:     deployment.targetEnv = mkOption {
        default = "none";
        example = "ec2";
        description = ''
          This option specifies the type of the environment in which the
          machine is to be deployed by
  
negative.code: 
      deployment.targetHost = mkOption {
        default = config.networking.hostName;
        type = types.uniq types.string;
        description = ''
          This option specifies a hostname or IP address which can be
          used by <command>nixos-deploy-network</command> to execute
  