new_contents: """Leetcode 701. Insert into a Binary Search Tree
  Medium
  
  URL: https://leetcode.com/problems/insert-into-a-binary-search-tree/
  
  Given the root node of a binary search tree (BST) and a value to be inserted 
  into the tree, insert the value into the BST. Return the root node of the BST 
  after the insertion. It is guaranteed that the new value does not exist in the
  original BST.
  
  Note that there may exist multiple valid ways for the insertion, as long as 
  the tree remains a BST after insertion. You can return any of them.
  
  For example, 
  Given the tree:
          4
         / \
        2   7
       / \
      1   3
  And the value to insert: 5
  You can return this binary search tree:
           4
         /   \
        2     7
       / \   /
      1   3 5
  This tree is also valid:
           5
         /   \
        2     7
       / \   
      1   3
           \
            4
  """
  
  # Definition for a binary tree node.
  class TreeNode(object):
      def __init__(self, x):
          self.val = x
          self.left = None
          self.right = None
  
  
  class Solution(object):
      def insertIntoBST(self, root, val):
          """
          :type root: TreeNode
          :type val: int
          :rtype: TreeNode
          """
          pass
  
  
  def main():
      pass
  
  
  if __name__ == '__main__':
      main()
  
subject: Add lc701_insert_into_a_binary_search_tree.py