code: func NodeFromLabels(labels map[string]string) *Node {
  	keys := []string{}
  	for key := range labels {
  		keys = append(keys, key)
  	}
  	// Sort the label to have a repeatable order
  	sort.Strings(keys)
  
  	labelPairs := []string{}
  	var rootNode *Node
  	var prevNode *Node
  	for _, key := range keys {
  		value := labels[key]
  		labelPairs = append(labelPairs, fmt.Sprintf("%q='%s'", key, value))
  		// Value must be single quoted to prevent env variable expansion
  		// See https://github.com/docker/docker/issues/26027
  		node := newKeyValueNode(key, "'"+value+"'")
  		rootNode, prevNode = appendKeyValueNode(node, rootNode, prevNode)
  	}
  
  	return &Node{
  		Value:    command.Label,
  		Original: commandLabel + " " + strings.Join(labelPairs, " "),
  		Next:     rootNode,
  	}
  }
docs: // NodeFromLabels returns a Node for the injected labels