You are an expert in writing code in many different languages. Your goal is to perform code completion for the following code, keeping in mind the rest of the code and the file meta data.
    Metadata details:
    filename: Solution.go
    path of file: ./repos/awesome-golang-algorithm/lcof/of037
    
    the code of the file until where you have to start completion: package Solution

import (
	"strconv"
	"strings"
)

type TreeNode struct {
	Val   int
	Left  *TreeNode
	Righ
    
func dfs(valsPtr *[]string) *TreeNode {
	val := (*valsPtr)[0]
	*valsPtr = (*valsPtr)[1:]
	if val == "nil" {
		return nil
	}
	valInt, _ := strconv.Atoi(val)
	node := &TreeNode{Val: valInt}
	node.Left = dfs(valsPtr)
	node.Right = dfs(valsPtr)
	return node
}