  
  class TestBstValidate(object):
  
      def test_bst_validate(self):
          node = Node(5)
          insert(node, 8)
          insert(node, 5)
          insert(node, 6)
 
</s>
    @raises(Exception)
    def test_bst_validate_empty(self):
        validate_bst(None)

  
  class TestBstValidate(object):
  
    @raises(Exception)
    def test_bst_validate_empty(self):
        validate_bst(None)

      def test_bst_validate(self):
          node = Node(5)
          insert(node, 8)
          insert(node, 5)
          insert(node, 6)
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