code: func (km *keyMutex) UnlockKey(id string) error {
  	glog.V(5).Infof("UnlockKey(...) called for id %q\r\n", id)
  	km.RLock()
  	defer km.RUnlock()
  	mutex, exists := km.mutexMap[id]
  	if !exists {
  		return fmt.Errorf("id %q not found", id)
  	}
  	glog.V(5).Infof("UnlockKey(...) for id. Mutex found, trying to unlock it. %q\r\n", id)
  
  	mutex.Unlock()
  	glog.V(5).Infof("UnlockKey(...) for id %q completed.\r\n", id)
  	return nil
  }
docs: // Releases the lock associated with the specified ID.
  // Returns an error if the specified ID doesn't exist.