code: func cmdPuppetCheckUpdates(params Parameters) *subcommands.Command {
  	return &subcommands.Command{
  		Advanced:  true,
  		UsageLine: "puppet-check-updates [options]",
  		ShortDesc: "returns 0 exit code iff 'ensure' will do some actions",
  		LongDesc: "Returns 0 exit code iff 'ensure' will do some actions.\n\n" +
  			"Exists to be used from Puppet's Exec 'onlyif' option to trigger " +
  			"'ensure' only if something is out of date. If puppet-check-updates " +
  			"fails with a transient error, it returns non-zero exit code (as usual), " +
  			"so that Puppet doesn't trigger notification chain (that can result in " +
  			"service restarts). On fatal errors it returns 0 to let Puppet run " +
  			"'ensure' for real and catch an error.",
  		CommandRun: func() subcommands.CommandRun {
  			c := &checkUpdatesRun{}
  			c.registerBaseFlags()
  			c.clientOptions.registerFlags(&c.Flags, params, withRootDir)
  			c.ensureFileOptions.registerFlags(&c.Flags, withoutEnsureOutFlag, withLegacyListFlag)
  			return c
  		},
  	}
  }
docs: ////////////////////////////////////////////////////////////////////////////////
  // 'puppet-check-updates' subcommand.