      "class TestStackMin(object):\n",
      "\n",
      "    def test_stack_min(self):\n",
      "        print('Test: Push on empty stack, non-empty stack')\n",
      "        stack = MyStack()\n",
      "        stack.push(5)\n",
      "        assert_equal(stack.peek(), 5)\n",
      "        assert_equal(stack.min(), 5)\n",
      "        stack.push(1)\n",
      "        assert_equal(stack.peek(), 1)\n",
 
</s>
    "        stack = StackMin()\n",
      "class TestStackMin(object):\n",
      "\n",
      "    def test_stack_min(self):\n",
      "        print('Test: Push on empty stack, non-empty stack')\n",
    "        stack = StackMin()\n",
      "        stack.push(5)\n",
      "        assert_equal(stack.peek(), 5)\n",
      "        assert_equal(stack.min(), 5)\n",
      "        stack.push(1)\n",
      "        assert_equal(stack.peek(), 1)\n",
keep keep keep keep replace keep keep keep keep keep
 Polish stack min challenge and solution (#72)

Update constraints, algorithm discussion, code, and tests.
stacks_queues/stack_min/stack_min_solution.ipynb