Golang customize once. When error occurs, reset it for the second time

package main

import (
	"log"
	"sync"
	"sync/atomic"
	"time"
)

//  A more powerful Once
type Oncev2 struct {
    
	m    sync.Mutex
	done uint32
}
//  Function passed in f There is a return value error, If initialization fails , You need to return the failed error
// Do The method will put this error Back to the caller 
func (o *Oncev2) Do(f func() error) error {
    
	if atomic.LoadUint32(&o.done) == 1 {
     //fast path
		return nil
	}
	return o.slowDo(f)
}
//  If it's not already initialized 
func (o *Oncev2) slowDo(f func() error) error {
    
	o.m.Lock()
	defer o.m.Unlock()
	var err error
	if o.done == 0 {
     //  Double check , It's not initialized yet 
		err = f()
		if err == nil {
     //  The flag is set to initialized only after initialization is successful 
			atomic.StoreUint32(&o.done, 1)
		}
	}
	return err
}

func main()  {
    
	var one =  &Oncev2{
    }
	for{
    
		time.Sleep(time.Second)
		err := one.Do(func() error {
    
			log.Println(" Do it once ")
			return nil
			//return errors.New(" error ")
		})
		log.Println(err)

	}
}