import pyutil as pyu
pyu.get_local_pyinfo()

print(pyu.ps2("python-dotenv"))

from typing import List

class Solution:
  def isValidBST(self, root: Optional[TreeNode]) -> bool:
    def isValidBST(root: Optional[TreeNode],
                   minNode: Optional[TreeNode], maxNode: Optional[TreeNode]) -> bool:
      if not root:
        return True
      if minNode and root.val <= minNode.val:
        return False
      if maxNode and root.val >= maxNode.val:
        return False

      return isValidBST(root.left, minNode, root) and \
          isValidBST(root.right, root, maxNode)

    return isValidBST(root, None, None)

new Solution().isValidBST()