new_contents: """
  Definition of TreeNode:
  class TreeNode:
      def __init__(self, val):
          self.val = val
          self.left, self.right = None, None
  """
  class Solution:
      # @param root: a TreeNode, the root of the binary tree
      # @return: nothing
      def invertBinaryTree(self, root):
          # write your code here
          if root == None:
              return
          root.left, root.right =  root.right, root.left
          self.invertBinaryTree(root.left)
          self.invertBinaryTree(root.right)
  
subject: Create invert-binary-tree.py