code: func containerResourceRuntimeValue(fs *v1.ResourceFieldSelector, pod *v1.Pod, container *v1.Container) (string, error) {
  	containerName := fs.ContainerName
  	if len(containerName) == 0 {
  		return resource.ExtractContainerResourceValue(fs, container)
  	}
  	return resource.ExtractResourceValueByContainerName(fs, pod, containerName)
  }
docs: // containerResourceRuntimeValue returns the value of the provided container resource