      "    def test_check_balance_empty(self):\n",
      "        check_balance(None)\n",
      "\n",
      "        node = Node(5)\n",
      "        assert_equal(check_balance(node), True)\n",
      "\n",
      "        insert(node, 3)\n",
 
</s> remove     "    def test_check_balance(self):\n",
    "        assert_equal(check_balance(None), False)\n",
 </s> add     "    @raises(Exception)\n",
    "    def test_check_balance_empty(self):\n",
    "        check_balance(None)\n", </s> remove     "    def test_check_balance(self):\n",
    "        assert_equal(check_balance(None), False)\n",
 </s> add     "    @raises(Exception)\n",
    "    def test_check_balance_empty(self):\n",
    "        check_balance(None)\n",
    "    def test_check_balance(self):\n",
      "    def test_check_balance_empty(self):\n",
      "        check_balance(None)\n",
      "\n",
    "    def test_check_balance(self):\n",
      "        node = Node(5)\n",
      "        assert_equal(check_balance(node), True)\n",
      "\n",
      "        insert(node, 3)\n",
keep keep add keep keep keep keep
 Polish bst check balanced challenge and solution (#84)

Update constraints, tests, and code. 
graphs_trees/check_balance/check_balance_solution.ipynb