code: func (km *keyMutex) getOrCreateLock(id string) *sync.Mutex {
  	km.Lock()
  	defer km.Unlock()
  
  	if _, exists := km.mutexMap[id]; !exists {
  		km.mutexMap[id] = &sync.Mutex{}
  	}
  
  	return km.mutexMap[id]
  }
docs: // Returns lock associated with the specified ID, or creates the lock if one doesn't already exist.