clientv3/concurrency/mutex.go
func NewLocker(s *Session, pfx string) sync.Locker {
	return &lockerMutex{NewMutex(s, pfx)}
}
func NewLocker(s *Session, pfx string) sync.Locker {
	return &lockerMutex{NewMutex(s, pfx)}
}
func NewLocker ( s * Session , pfx string ) sync . Locker { return & lockerMutex { NewMutex ( s , pfx ) } }
// NewLocker creates a sync.Locker backed by an etcd mutex.
NewLocker creates a sync . Locker backed by an etcd mutex .