func (s *threadSafeStorage) lockR() func() {
	s.RLock()
	return func() { s.RUnlock() }
}
lockR locks storage for reading
package memory
import "sync"
type threadSafeStorage struct {
	sync.RWMutex
}
func (s *threadSafeStorage) lockW() func() {
	s.Lock()
	return func() { s.Unlock() }
}