      "%%writefile test_bst_successor.py\n",
      "from nose.tools import assert_equal\n",
      "\n",
      "\n",
      "class TestBstSuccessor(object):\n",
      "\n",
      "    @raises(Exception)\n",
      "    def test_bst_successor_empty(self):\n",
 
</s>
    "from nose.tools import raises\n",
      "%%writefile test_bst_successor.py\n",
      "from nose.tools import assert_equal\n",
    "from nose.tools import raises\n",
      "\n",
      "\n",
      "class TestBstSuccessor(object):\n",
      "\n",
      "    @raises(Exception)\n",
      "    def test_bst_successor_empty(self):\n",
keep add keep keep keep keep keep keep
 Polish bst successor challenge and solution (#82)

Update constraints, test cases, tests, algorithm discussion, and code.
graphs_trees/bst_successor/bst_successor_solution.ipynb