code: func (engine *DockerStatsEngine) addToStatsContainerMapUnsafe(
  	taskARN, containerID string,
  	statsContainer *StatsContainer,
  	statsMapToUpdate func() map[string]map[string]*StatsContainer) bool {
  
  	taskToContainerMap := statsMapToUpdate()
  
  	// Check if this container is already being watched.
  	_, taskExists := taskToContainerMap[taskARN]
  	if taskExists {
  		// task arn exists in map.
  		_, containerExists := taskToContainerMap[taskARN][containerID]
  		if containerExists {
  			// container arn exists in map.
  			seelog.Debugf("Container already being watched, ignoring, id: %s", containerID)
  			return false
  		}
  	} else {
  		// Create a map for the task arn if it doesn't exist yet.
  		taskToContainerMap[taskARN] = make(map[string]*StatsContainer)
  	}
  	taskToContainerMap[taskARN][containerID] = statsContainer
  
  	return true
  }
docs: // addToStatsContainerMapUnsafe adds the statscontainer into stats for tracking and returns a boolean indicates
  // whether this container should be tracked for collecting metrics