     ]
    },
    {
     "cell_type": "code",
     "execution_count": 3,
     "metadata": {
      "collapsed": false
     },
     "outputs": [],
     "source": [
 
</s> remove    "execution_count": 4,
 </s> add    "execution_count": null, </s> remove    "outputs": [
    {
     "name": "stdout",
     "output_type": "stream",
     "text": [
      "Success: test_unique_chars\n"
     ]
    }
   ],
 </s> add    "outputs": [], </s> remove     "    chars_set = set()\n",
    "    for char in string:\n",
    "        if char in chars_set:\n",
    "            return False\n",
    "        else:\n",
    "            chars_set.add(char)\n",
    "    return True"
 </s> add     "    # TODO: Implement me\n",
    "    pass"
   "execution_count": null,
     ]
    },
    {
     "cell_type": "code",
   "execution_count": null,
     "metadata": {
      "collapsed": false
     },
     "outputs": [],
     "source": [
keep keep keep keep replace keep keep keep keep keep
 Set solution to blank for unique chars challenge. 
arrays_strings/unique_chars/unique_chars_challenge.ipynb