  
  def main():
      test = TestCheckBalance()
      test.test_check_balance()
  
  
  if __name__ == '__main__':
      main() 
</s> remove     "    if not root:\n",
 </s> add     "    if root is None:\n", </s> remove     "        return False\n",
 </s> add     "        raise Exception('No root node')\n",
    test.test_check_balance_empty()
  
  def main():
      test = TestCheckBalance()
    test.test_check_balance_empty()
      test.test_check_balance()
  
  
  if __name__ == '__main__':
      main() 
keep keep add keep keep keep keep keep
 Polish bst check balanced challenge and solution (#84)

Update constraints, tests, and code. 
graphs_trees/check_balance/test_check_balance.py