"""
# Definition for a Node.
class Node:
def __init__(self, val=None, children=None):
self.val = val
self.children = children
"""
class Solution:
def preorder(self, root: 'Node') -> List[int]:
res = []
def dfs(root):
if not root:
return res
res.append(root.val)
for node in root.children:
dfs(node)
return res
return dfs(root)
