  
  
  def main():
      test = TestBstValidate()
      test.test_bst_validate()
  
  
  if __name__ == '__main__':
      main() 
</s>
    test.test_bst_validate_empty()
  
  
  def main():
      test = TestBstValidate()
    test.test_bst_validate_empty()
      test.test_bst_validate()
  
  
  if __name__ == '__main__':
      main() 
keep keep keep add keep keep keep keep keep
 Polish bst validate challenge and solution (#83)

Update constraints, test cases, tests, algorithm discussion, and code.
graphs_trees/bst_validate/test_bst_validate.py