     },
     "outputs": [],
     "source": [
      "def unique_chars(string):\n",
      "    return len(set(string)) == len(string)\n",
      "\n",
      "run_tests(unique_chars)"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
 
</s> remove     "    return True\n",
 </s> add     "    return True"
   ]
  },
  {
   "cell_type": "markdown",
   "metadata": {},
   "source": [
    "## Unit Test"
   ]
  },
  {
   "cell_type": "code",
   "execution_count": 4,
   "metadata": {
    "collapsed": false
   },
   "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Success: test_unique_chars\n",
      "Success: test_unique_chars\n",
      "Success: test_unique_chars\n"
     ]
    }
   ],
   "source": [
    "from nose.tools import assert_equal\n", </s> remove   {
   "cell_type": "code",
   "execution_count": null,
   "metadata": {
    "collapsed": false
   },
   "outputs": [],
   "source": [
    "from nose.tools import assert_equal\n",
    "\n",
    "class Test(object):\n",
    "  def test_unique_chars(self, func):\n",
    "        assert_equal(func(''), True)\n",
    "        assert_equal(func('foo'), False)\n",
    "        assert_equal(func('bar'), True)\n",
    "\n",
    "def run_tests(func):\n",
    "    test = Test()\n",
    "    test.test_unique_chars(func)"
   ]
  },
 </s> add  </s> remove     "    return True\n",
    "\n",
    "run_tests(unique_chars_hash)"
 </s> add     "    return True" </s> remove    "execution_count": null,
 </s> add    "execution_count": 3, </s> remove    "execution_count": null,
 </s> add    "execution_count": 2,
    "    return len(set(string)) == len(string)"
     },
     "outputs": [],
     "source": [
      "def unique_chars(string):\n",
    "    return len(set(string)) == len(string)"
    "    return len(set(string)) == len(string)"
    "    return len(set(string)) == len(string)"
     ]
    },
    {
     "cell_type": "markdown",
     "metadata": {},
keep keep keep keep replace replace replace keep keep keep keep keep
 Reworked notebook: Added more detail to clarifying questions and test cases.  Reworked unit test. 
arrays-strings/unique_chars.ipynb