code: func (state *DockerTaskEngineState) RemoveImageState(imageState *image.ImageState) {
  	if imageState == nil {
  		log.Debug("Cannot remove empty image state")
  		return
  	}
  	state.lock.Lock()
  	defer state.lock.Unlock()
  
  	imageState, ok := state.imageStates[imageState.Image.ImageID]
  	if !ok {
  		log.Debug("Image State is not found. Cannot be removed")
  		return
  	}
  	delete(state.imageStates, imageState.Image.ImageID)
  }
docs: // RemoveImageState removes an image.ImageState