589. N-ary Tree Preorder Traversal - LeetCode Solution

"""
# 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]:
        a = []
        
        def trav(root):

            if not root:
                return 
            
            a.append(root.val)
            
            for i in range(len(root.children)):
                trav(root.children[i])
        trav(root)
        return a