diff --git a/ipynb/Fred Buns.ipynb b/ipynb/Fred Buns.ipynb
index 47ed555..7bf374d 100644
--- a/ipynb/Fred Buns.ipynb	
+++ b/ipynb/Fred Buns.ipynb	
@@ -4,7 +4,7 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "<div style=\"float:right\"><i>Peter Norvig, 15 June 2015</i></div>"
+    "<div align=\"right\"><i>Peter Norvig, 15 June 2015</i></div>"
    ]
   },
   {
@@ -50,9 +50,7 @@
   {
    "cell_type": "code",
    "execution_count": 1,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "from   __future__ import division, print_function # To work in Python 2.x or 3.x\n",
@@ -75,9 +73,7 @@
   {
    "cell_type": "code",
    "execution_count": 2,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "fredbuns = ['FB', 'RU', 'EN', 'DS'] # A lock with two letters on each of four tumblers"
@@ -93,9 +89,7 @@
   {
    "cell_type": "code",
    "execution_count": 3,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [
     {
      "data": {
@@ -137,9 +131,7 @@
   {
    "cell_type": "code",
    "execution_count": 4,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "def combinations(lock):\n",
@@ -150,9 +142,7 @@
   {
    "cell_type": "code",
    "execution_count": 5,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [
     {
      "data": {
@@ -197,9 +187,7 @@
   {
    "cell_type": "code",
    "execution_count": 6,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "! [ -e words4.txt ] || curl -O http://norvig.com/ngrams/words4.txt"
@@ -215,9 +203,7 @@
   {
    "cell_type": "code",
    "execution_count": 7,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [
     {
      "name": "stdout",
@@ -250,9 +236,7 @@
   {
    "cell_type": "code",
    "execution_count": 8,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "WORDS = set(open('words4.txt').read().split())"
@@ -261,9 +245,7 @@
   {
    "cell_type": "code",
    "execution_count": 9,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [
     {
      "data": {
@@ -290,9 +272,7 @@
   {
    "cell_type": "code",
    "execution_count": 10,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "def words_from(lock): \n",
@@ -303,9 +283,7 @@
   {
    "cell_type": "code",
    "execution_count": 11,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [
     {
      "data": {
@@ -332,9 +310,7 @@
   {
    "cell_type": "code",
    "execution_count": 12,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "def show(lock):\n",
@@ -349,9 +325,7 @@
   {
    "cell_type": "code",
    "execution_count": 13,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [
     {
      "name": "stdout",
@@ -391,9 +365,7 @@
   {
    "cell_type": "code",
    "execution_count": 14,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "wordlock = ['SPHMTWDLFB', 'LEYHNRUOAI', 'ENMLRTAOSK', 'DSNMPYLKTE']"
@@ -402,9 +374,7 @@
   {
    "cell_type": "code",
    "execution_count": 15,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [
     {
      "name": "stdout",
@@ -451,9 +421,7 @@
   {
    "cell_type": "code",
    "execution_count": 16,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "def random_lock(t=4, c=10, seed='seed'):\n",
@@ -468,9 +436,7 @@
   {
    "cell_type": "code",
    "execution_count": 17,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [
     {
      "name": "stdout",
@@ -496,9 +462,7 @@
   {
    "cell_type": "code",
    "execution_count": 18,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "def word_count(lock): return len(words_from(lock))"
@@ -507,9 +471,7 @@
   {
    "cell_type": "code",
    "execution_count": 19,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [
     {
      "name": "stdout",
@@ -551,9 +513,7 @@
   {
    "cell_type": "code",
    "execution_count": 20,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [
     {
      "data": {
@@ -591,9 +551,7 @@
   {
    "cell_type": "code",
    "execution_count": 21,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [
     {
      "data": {
@@ -624,9 +582,7 @@
   {
    "cell_type": "code",
    "execution_count": 22,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "def greedy_lock(t=4, c=10, words=WORDS):\n",
@@ -645,9 +601,7 @@
   {
    "cell_type": "code",
    "execution_count": 23,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [
     {
      "name": "stdout",
@@ -695,9 +649,7 @@
   {
    "cell_type": "code",
    "execution_count": 24,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "def improved_lock(lock, steps=3000):\n",
@@ -730,9 +682,7 @@
   {
    "cell_type": "code",
    "execution_count": 25,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [
     {
      "name": "stdout",
@@ -758,16 +708,14 @@
   {
    "cell_type": "code",
    "execution_count": 26,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [
     {
      "name": "stdout",
      "output_type": "stream",
      "text": [
-      "CPU times: user 6min 50s, sys: 1.44 s, total: 6min 51s\n",
-      "Wall time: 6min 53s\n"
+      "CPU times: user 4min 54s, sys: 1.68 s, total: 4min 56s\n",
+      "Wall time: 4min 59s\n"
      ]
     }
    ],
@@ -785,9 +733,7 @@
   {
    "cell_type": "code",
    "execution_count": 27,
-   "metadata": {
-    "collapsed": false
-   },
+   "metadata": {},
    "outputs": [
     {
      "data": {
@@ -815,9 +761,7 @@
   {
    "cell_type": "code",
    "execution_count": 28,
-   "metadata": {
-    "collapsed": true
-   },
+   "metadata": {},
    "outputs": [],
    "source": [
     "def alock(lock):\n",
@@ -834,10 +778,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 47,
-   "metadata": {
-    "collapsed": false
-   },
+   "execution_count": 29,
+   "metadata": {},
    "outputs": [
     {
      "data": {
@@ -853,7 +795,7 @@
        " ('BCDLMPRSTW', 'AEHILORUWY', 'ACEILNORST', 'ADEHKLNSTY'): 1237}"
       ]
      },
-     "execution_count": 47,
+     "execution_count": 29,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -876,10 +818,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 48,
-   "metadata": {
-    "collapsed": false
-   },
+   "execution_count": 30,
+   "metadata": {},
    "outputs": [
     {
      "data": {
@@ -888,7 +828,7 @@
        " ('BCDFLMPSTW', 'AEHILORUWY', 'ACEILNORST', 'ADEHKLNSTY')}"
       ]
      },
-     "execution_count": 48,
+     "execution_count": 30,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -926,10 +866,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 49,
-   "metadata": {
-    "collapsed": false
-   },
+   "execution_count": 31,
+   "metadata": {},
    "outputs": [],
    "source": [
     "def transpose(strings): return [Word(letters) for letters in zip(*strings)]"
@@ -944,10 +882,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 50,
-   "metadata": {
-    "collapsed": false
-   },
+   "execution_count": 32,
+   "metadata": {},
    "outputs": [
     {
      "data": {
@@ -964,7 +900,7 @@
        " 'BIKE']"
       ]
      },
-     "execution_count": 50,
+     "execution_count": 32,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -996,10 +932,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 51,
-   "metadata": {
-    "collapsed": false
-   },
+   "execution_count": 33,
+   "metadata": {},
    "outputs": [],
    "source": [
     "def improved_wordlist(wordlist):\n",
@@ -1041,27 +975,25 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 52,
-   "metadata": {
-    "collapsed": false
-   },
+   "execution_count": 34,
+   "metadata": {},
    "outputs": [
     {
      "data": {
       "text/plain": [
-       "['RAID',\n",
-       " 'ANSH',\n",
-       " 'OYER',\n",
-       " 'UPON',\n",
-       " 'KUDU',\n",
-       " 'GLUM',\n",
-       " 'JIMP',\n",
-       " 'IFFY',\n",
-       " 'NEVE',\n",
-       " 'FOAL']"
+       "['HWAN',\n",
+       " 'GETA',\n",
+       " 'LOCI',\n",
+       " 'FIRS',\n",
+       " 'TYNE',\n",
+       " 'SAIF',\n",
+       " 'ELMY',\n",
+       " 'AVER',\n",
+       " 'DUSK',\n",
+       " 'PROG']"
       ]
      },
-     "execution_count": 52,
+     "execution_count": 34,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1079,28 +1011,26 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 53,
-   "metadata": {
-    "collapsed": false
-   },
+   "execution_count": 35,
+   "metadata": {},
    "outputs": [
     {
      "data": {
       "text/plain": [
-       "['AMAH',\n",
-       " 'HARM',\n",
-       " 'UPDO',\n",
-       " 'LIVE',\n",
-       " 'GWEN',\n",
-       " 'FELT',\n",
-       " 'MUFF',\n",
-       " 'ROTI',\n",
-       " 'SCUP',\n",
-       " 'EDGY',\n",
-       " 'BROS']"
+       "['LIDO',\n",
+       " 'GLIB',\n",
+       " 'HERS',\n",
+       " 'IDOL',\n",
+       " 'CHEW',\n",
+       " 'JUKU',\n",
+       " 'ARYA',\n",
+       " 'POUT',\n",
+       " 'RAGE',\n",
+       " 'ONLY',\n",
+       " 'SPAR']"
       ]
      },
-     "execution_count": 53,
+     "execution_count": 35,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1137,10 +1067,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 54,
-   "metadata": {
-    "collapsed": false
-   },
+   "execution_count": 36,
+   "metadata": {},
    "outputs": [],
    "source": [
     "def improved(item, changed, scorer, extremum, stop):\n",
@@ -1165,10 +1093,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 55,
-   "metadata": {
-    "collapsed": false
-   },
+   "execution_count": 37,
+   "metadata": {},
    "outputs": [],
    "source": [
     "def improved_lock(lock, steps=3000):\n",
@@ -1184,10 +1110,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 56,
-   "metadata": {
-    "collapsed": false
-   },
+   "execution_count": 38,
+   "metadata": {},
    "outputs": [
     {
      "name": "stdout",
@@ -1205,27 +1129,25 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 57,
-   "metadata": {
-    "collapsed": false
-   },
+   "execution_count": 39,
+   "metadata": {},
    "outputs": [
     {
      "data": {
       "text/plain": [
-       "['TUBA',\n",
-       " 'PROF',\n",
-       " 'AXAL',\n",
-       " 'SCUD',\n",
-       " 'YAWN',\n",
-       " 'FLEY',\n",
-       " 'EGGS',\n",
-       " 'BILK',\n",
-       " 'CHIT',\n",
-       " 'LEHR']"
+       "['NICK',\n",
+       " 'HEED',\n",
+       " 'DOTH',\n",
+       " 'GRIP',\n",
+       " 'KHAF',\n",
+       " 'ELMY',\n",
+       " 'FURS',\n",
+       " 'ICON',\n",
+       " 'UNBE',\n",
+       " 'CALO']"
       ]
      },
-     "execution_count": 57,
+     "execution_count": 39,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1255,10 +1177,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 58,
-   "metadata": {
-    "collapsed": false
-   },
+   "execution_count": 40,
+   "metadata": {},
    "outputs": [],
    "source": [
     "def greedy_lock_patented(t=4, c=10, words=WORDS):\n",
@@ -1276,10 +1196,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 59,
-   "metadata": {
-    "collapsed": false
-   },
+   "execution_count": 41,
+   "metadata": {},
    "outputs": [
     {
      "data": {
@@ -1287,7 +1205,7 @@
        "1177"
       ]
      },
-     "execution_count": 59,
+     "execution_count": 41,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1298,10 +1216,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 60,
-   "metadata": {
-    "collapsed": false
-   },
+   "execution_count": 42,
+   "metadata": {},
    "outputs": [
     {
      "data": {
@@ -1309,7 +1225,7 @@
        "1161"
       ]
      },
-     "execution_count": 60,
+     "execution_count": 42,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1335,10 +1251,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 61,
-   "metadata": {
-    "collapsed": false
-   },
+   "execution_count": 43,
+   "metadata": {},
    "outputs": [
     {
      "data": {
@@ -1346,7 +1260,7 @@
        "'pass'"
       ]
      },
-     "execution_count": 61,
+     "execution_count": 43,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1380,6 +1294,39 @@
     "tests()"
    ]
   },
+  {
+   "cell_type": "markdown",
+   "metadata": {},
+   "source": [
+    "# Addendum: 2018\n",
+    "\n",
+    "New [research](https://www.theverge.com/2018/10/7/17940352/turing-test-one-word-minimal-human-ai-machine-poop) suggests that the one word that humans are most likely to think was generated by another human rather than by a machine is *\"poop\"*. Is it a coincidence that the same week this research came out, I was in a bike shop and saw the following:\n",
+    "\n",
+    "![](like.jpg)\n",
+    "\n",
+    "This proves that I'm not the only one with a juvenile reaction to the *WordLock*®, but it raises some questions: Was the last visitor to the store a human asserting their individuality? Or a robot yearning to be free? Or [Triumph the insult comic dog](https://en.wikipedia.org/wiki/Triumph_the_Insult_Comic_Dog)? I guess we'll never know."
+   ]
+  },
+  {
+   "cell_type": "code",
+   "execution_count": 44,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "True"
+      ]
+     },
+     "execution_count": 44,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
+   "source": [
+    "'POOP' in WORDS"
+   ]
+  },
   {
    "cell_type": "markdown",
    "metadata": {},
@@ -1396,10 +1343,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 62,
-   "metadata": {
-    "collapsed": false
-   },
+   "execution_count": 45,
+   "metadata": {},
    "outputs": [
     {
      "data": {
@@ -1407,7 +1352,7 @@
        "{7, 15, 23, 28, 31, 39, 47, 55, 60, 63, 71, 79, 87, 92, 95}"
       ]
      },
-     "execution_count": 62,
+     "execution_count": 45,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1436,9 +1381,9 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.6.0"
+   "version": "3.5.3"
   }
  },
  "nbformat": 4,
- "nbformat_minor": 0
+ "nbformat_minor": 1
 }
diff --git a/ipynb/like.jpg b/ipynb/like.jpg
new file mode 100644
index 0000000..8d2c508
Binary files /dev/null and b/ipynb/like.jpg differ