message: Update encode-n-ary-tree-to-binary-tree.py
diff: # Time: O(n)
  # Space: O(h)
  -"""
  # Definition for a Node.
  class Node(object):
  def __init__(self, val, children):
  self.val = val
  self.children = children
  -"""
  -"""
  +
  +
  # Definition for a binary tree node.
  class TreeNode(object):
  def __init__(self, x):
  self.val = x
  self.left = None
  self.right = None
  -"""
  +
  +
  class Codec:
  def encode(self, root):
  