  
  def main():
      test = TestBstSuccessor()
      test.test_bst_successor()
  
  
  if __name__ == '__main__':
      main() 
</s>
    test.test_bst_successor_empty()
  
  def main():
      test = TestBstSuccessor()
      test.test_bst_successor()
    test.test_bst_successor_empty()
  
  
  if __name__ == '__main__':
      main() 
keep keep keep add keep keep keep keep
 Polish bst successor challenge and solution (#82)

Update constraints, test cases, tests, algorithm discussion, and code.
graphs_trees/bst_successor/test_bst_successor.py