code: func extractContainerResourceValue(fs *corev1.ResourceFieldSelector, container *corev1.Container) (string, error) {
  	divisor := resource.Quantity{}
  	if divisor.Cmp(fs.Divisor) == 0 {
  		divisor = resource.MustParse("1")
  	} else {
  		divisor = fs.Divisor
  	}
  
  	switch fs.Resource {
  	case "limits.cpu":
  		return convertResourceCPUToString(container.Resources.Limits.Cpu(), divisor)
  	case "limits.memory":
  		return convertResourceMemoryToString(container.Resources.Limits.Memory(), divisor)
  	case "limits.ephemeral-storage":
  		return convertResourceEphemeralStorageToString(container.Resources.Limits.StorageEphemeral(), divisor)
  	case "requests.cpu":
  		return convertResourceCPUToString(container.Resources.Requests.Cpu(), divisor)
  	case "requests.memory":
  		return convertResourceMemoryToString(container.Resources.Requests.Memory(), divisor)
  	case "requests.ephemeral-storage":
  		return convertResourceEphemeralStorageToString(container.Resources.Requests.StorageEphemeral(), divisor)
  	}
  
  	return "", fmt.Errorf("Unsupported container resource : %v", fs.Resource)
  }
docs: // ExtractContainerResourceValue extracts the value of a resource
  // in an already known container