anchor.diff:      deployment.ec2.type = mkOption {
         default = "ec2";
         example = "nova";
  +      type = types.uniq types.string;
         description = ''
           Specifies the type of cloud.  This affects the machine
           configuration.  Current values are <literal>"ec2"</literal>
  
positive.code: 
      deployment.adhoc.destroyVMCommand = mkOption {
        default = "destroy-vm";
        description = ''
          Remote command to destroy a previously created NixOS virtual
          machine.
  
negative.code:     deployment.targetEnv = mkOption {
        default = "none";
        example = "ec2";
        type = types.uniq types.string;
        description = ''
          This option specifies the type of the environment in which the
          machine is to be deployed by
  