code: func makedag(ctx *cli.Context) error {
  	args := ctx.Args()
  	if len(args) != 2 {
  		utils.Fatalf(`Usage: geth makedag <block number> <outputdir>`)
  	}
  	block, err := strconv.ParseUint(args[0], 0, 64)
  	if err != nil {
  		utils.Fatalf("Invalid block number: %v", err)
  	}
  	ethash.MakeDataset(block, args[1])
  
  	return nil
  }
docs: // makedag generates an ethash mining DAG into the provided folder.