diff --git a/index.ipynb b/index.ipynb
index 544f3fe500..c9ddd3ffb5 100644
--- a/index.ipynb
+++ b/index.ipynb
@@ -96,7 +96,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 76,
+   "execution_count": 2,
    "metadata": {},
    "outputs": [
     {
@@ -116,7 +116,7 @@
        " 'South Korea']"
       ]
      },
-     "execution_count": 76,
+     "execution_count": 2,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -134,10 +134,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 2,
-   "metadata": {
-    "collapsed": true
-   },
+   "execution_count": 6,
+   "metadata": {},
    "outputs": [],
    "source": [
     "top_travel_cities = ['Solta', 'Greenville', 'Buenos Aires', 'Los Cabos', 'Walla Walla Valley', 'Marakesh', 'Albuquerque', 'Archipelago Sea', 'Iguazu Falls', 'Salina Island', 'Toronto', 'Pyeongchang']"
@@ -145,7 +143,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 3,
+   "execution_count": 7,
    "metadata": {},
    "outputs": [
     {
@@ -165,7 +163,7 @@
        " 'Pyeongchang']"
       ]
      },
-     "execution_count": 3,
+     "execution_count": 7,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -176,10 +174,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 4,
-   "metadata": {
-    "collapsed": true
-   },
+   "execution_count": 8,
+   "metadata": {},
    "outputs": [],
    "source": [
     "countries_of_top_cities = ['Croatia', 'USA', 'Argentina', 'Mexico', 'USA', 'Morocco', 'New Mexico', 'Finland', 'Argentina', 'Italy', 'Canada', 'South Korea']"
@@ -212,7 +208,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 5,
+   "execution_count": 9,
    "metadata": {},
    "outputs": [
     {
@@ -232,7 +228,7 @@
        " 'Pyeongchang']"
       ]
      },
-     "execution_count": 5,
+     "execution_count": 9,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -243,22 +239,28 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 6,
+   "execution_count": 10,
    "metadata": {},
    "outputs": [
     {
      "data": {
       "text/plain": [
-       "'Solta'"
+       "['Solta', 'Greenville', 'Buenos Aires']"
       ]
      },
-     "execution_count": 6,
+     "execution_count": 10,
      "metadata": {},
      "output_type": "execute_result"
     }
    ],
    "source": [
-    "top_travel_cities[0]"
+    "top_travel_cities[0] \n",
+    "\n",
+    "number_one_top_travel_cities = top_travel_cities[0]\n",
+    "\n",
+    "top_three = top_travel_cities[0:3]\n",
+    "\n",
+    "top_three\n"
    ]
   },
   {
@@ -272,7 +274,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 82,
+   "execution_count": 11,
    "metadata": {},
    "outputs": [
     {
@@ -281,7 +283,7 @@
        "'Buenos Aires'"
       ]
      },
-     "execution_count": 82,
+     "execution_count": 11,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -299,7 +301,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 83,
+   "execution_count": 12,
    "metadata": {},
    "outputs": [
     {
@@ -308,7 +310,7 @@
        "'Pyeongchang'"
       ]
      },
-     "execution_count": 83,
+     "execution_count": 12,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -326,7 +328,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 84,
+   "execution_count": 15,
    "metadata": {},
    "outputs": [
     {
@@ -335,7 +337,7 @@
        "'Toronto'"
       ]
      },
-     "execution_count": 84,
+     "execution_count": 15,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -348,12 +350,12 @@
    "cell_type": "markdown",
    "metadata": {},
    "source": [
-    "Each element in our list is a string, so, we can always set an element of our string equal to a variable."
+    "Each element in our list is a string, so, we can always set an element of our string equal to a variable. "
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 85,
+   "execution_count": 16,
    "metadata": {},
    "outputs": [
     {
@@ -362,7 +364,7 @@
        "'Toronto'"
       ]
      },
-     "execution_count": 85,
+     "execution_count": 16,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -374,7 +376,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 86,
+   "execution_count": 17,
    "metadata": {},
    "outputs": [
     {
@@ -383,7 +385,7 @@
        "str"
       ]
      },
-     "execution_count": 86,
+     "execution_count": 17,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -401,7 +403,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 7,
+   "execution_count": 18,
    "metadata": {},
    "outputs": [
     {
@@ -421,7 +423,7 @@
        " 'Pyeongchang']"
       ]
      },
-     "execution_count": 7,
+     "execution_count": 18,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -432,7 +434,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 8,
+   "execution_count": 19,
    "metadata": {},
    "outputs": [
     {
@@ -441,7 +443,7 @@
        "list"
       ]
      },
-     "execution_count": 8,
+     "execution_count": 19,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -495,29 +497,19 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 90,
+   "execution_count": 1,
    "metadata": {},
    "outputs": [
     {
-     "data": {
-      "text/plain": [
-       "['Solta',\n",
-       " 'Greenville',\n",
-       " 'Buenos Aires',\n",
-       " 'Los Cabos',\n",
-       " 'Walla Walla Valley',\n",
-       " 'Marakesh',\n",
-       " 'Albuquerque',\n",
-       " 'Archipelago Sea',\n",
-       " 'Iguazu Falls',\n",
-       " 'Salina Island',\n",
-       " 'Toronto',\n",
-       " 'Pyeongchang']"
-      ]
-     },
-     "execution_count": 90,
-     "metadata": {},
-     "output_type": "execute_result"
+     "ename": "NameError",
+     "evalue": "name 'top_travel_cities' is not defined",
+     "output_type": "error",
+     "traceback": [
+      "\u001b[0;31m\u001b[0m",
+      "\u001b[0;31mNameError\u001b[0mTraceback (most recent call last)",
+      "\u001b[0;32m<ipython-input-1-9b35bd78de60>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0mtop_travel_cities\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
+      "\u001b[0;31mNameError\u001b[0m: name 'top_travel_cities' is not defined"
+     ]
     }
    ],
    "source": [
@@ -533,7 +525,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 91,
+   "execution_count": 3,
    "metadata": {},
    "outputs": [
     {
@@ -542,13 +534,14 @@
        "['Walla Walla Valley']"
       ]
      },
-     "execution_count": 91,
+     "execution_count": 3,
      "metadata": {},
      "output_type": "execute_result"
     }
    ],
    "source": [
-    "top_travel_cities[4:5]"
+    "top_travel_cities = ['Solta', 'Greenville', 'Buenos Aires', 'Los Cabos', 'Walla Walla Valley', 'Marakesh', 'Albuquerque', 'Archipelago Sea', 'Iguazu Falls', 'Salina Island', 'Toronto', 'Pyeongchang']\n",
+    "top_travel_cities[4:5]\n"
    ]
   },
   {
@@ -560,7 +553,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 10,
+   "execution_count": 4,
    "metadata": {},
    "outputs": [
     {
@@ -569,7 +562,7 @@
        "['Walla Walla Valley', 'Marakesh']"
       ]
      },
-     "execution_count": 10,
+     "execution_count": 4,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -587,7 +580,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 11,
+   "execution_count": 5,
    "metadata": {},
    "outputs": [
     {
@@ -607,7 +600,7 @@
        " 'Pyeongchang']"
       ]
      },
-     "execution_count": 11,
+     "execution_count": 5,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -667,13 +660,36 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 13,
-   "metadata": {
-    "collapsed": true
-   },
-   "outputs": [],
+   "execution_count": 6,
+   "metadata": {},
+   "outputs": [
+    {
+     "data": {
+      "text/plain": [
+       "['Solta',\n",
+       " 'Greenville',\n",
+       " 'Buenos Aires',\n",
+       " 'Los Cabos',\n",
+       " 'Walla Walla Valley',\n",
+       " 'Marakesh',\n",
+       " 'Albuquerque',\n",
+       " 'Archipelago Sea',\n",
+       " 'Iguazu Falls',\n",
+       " 'Salina Island',\n",
+       " 'Toronto',\n",
+       " 'Pyeongchang',\n",
+       " 'San Antonio']"
+      ]
+     },
+     "execution_count": 6,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
    "source": [
-    "top_travel_cities.append('San Antonio')"
+    "top_travel_cities = ['Solta', 'Greenville', 'Buenos Aires', 'Los Cabos', 'Walla Walla Valley', 'Marakesh', 'Albuquerque', 'Archipelago Sea', 'Iguazu Falls', 'Salina Island', 'Toronto', 'Pyeongchang']\n",
+    "top_travel_cities.append('San Antonio')\n",
+    "top_travel_cities"
    ]
   },
   {
@@ -685,7 +701,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 14,
+   "execution_count": 7,
    "metadata": {},
    "outputs": [
     {
@@ -706,7 +722,7 @@
        " 'San Antonio']"
       ]
      },
-     "execution_count": 14,
+     "execution_count": 7,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -724,7 +740,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 15,
+   "execution_count": 1,
    "metadata": {},
    "outputs": [
     {
@@ -742,16 +758,17 @@
        " 'Salina Island',\n",
        " 'Toronto',\n",
        " 'Pyeongchang',\n",
-       " 'San Antonio',\n",
        " 'San Antonio']"
       ]
      },
-     "execution_count": 15,
+     "execution_count": 1,
      "metadata": {},
      "output_type": "execute_result"
     }
    ],
    "source": [
+    "top_travel_cities = ['Solta', 'Greenville', 'Buenos Aires', 'Los Cabos', 'Walla Walla Valley', 'Marakesh', 'Albuquerque', \n",
+    "                     'Archipelago Sea', 'Iguazu Falls', 'Salina Island', 'Toronto', 'Pyeongchang']\n",
     "top_travel_cities.append('San Antonio')\n",
     "top_travel_cities"
    ]
@@ -765,22 +782,34 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 16,
+   "execution_count": 3,
    "metadata": {},
    "outputs": [
     {
      "data": {
       "text/plain": [
-       "'San Antonio'"
+       "['Solta',\n",
+       " 'Greenville',\n",
+       " 'Buenos Aires',\n",
+       " 'Los Cabos',\n",
+       " 'Walla Walla Valley',\n",
+       " 'Marakesh',\n",
+       " 'Albuquerque',\n",
+       " 'Archipelago Sea',\n",
+       " 'Iguazu Falls',\n",
+       " 'Salina Island',\n",
+       " 'Toronto']"
       ]
      },
-     "execution_count": 16,
+     "execution_count": 3,
      "metadata": {},
      "output_type": "execute_result"
     }
    ],
    "source": [
-    "top_travel_cities.pop()"
+    "top_travel_cities.pop()\n",
+    "\n",
+    "top_travel_cities"
    ]
   },
   {
@@ -792,7 +821,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 17,
+   "execution_count": 4,
    "metadata": {},
    "outputs": [
     {
@@ -801,7 +830,7 @@
        "'Walla Walla Valley'"
       ]
      },
-     "execution_count": 17,
+     "execution_count": 4,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -812,10 +841,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 18,
-   "metadata": {
-    "collapsed": true
-   },
+   "execution_count": 5,
+   "metadata": {},
    "outputs": [],
    "source": [
     "top_travel_cities[4] = 4"
@@ -823,7 +850,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 19,
+   "execution_count": 6,
    "metadata": {},
    "outputs": [
     {
@@ -839,12 +866,10 @@
        " 'Archipelago Sea',\n",
        " 'Iguazu Falls',\n",
        " 'Salina Island',\n",
-       " 'Toronto',\n",
-       " 'Pyeongchang',\n",
-       " 'San Antonio']"
+       " 'Toronto']"
       ]
      },
-     "execution_count": 19,
+     "execution_count": 6,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -926,10 +951,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 22,
-   "metadata": {
-    "collapsed": true
-   },
+   "execution_count": 2,
+   "metadata": {},
    "outputs": [],
    "source": [
     "top_travel_cities.append('Solta')"
@@ -951,7 +974,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 23,
+   "execution_count": 7,
    "metadata": {},
    "outputs": [
     {
@@ -972,7 +995,7 @@
        " 'Walla Walla Valley'}"
       ]
      },
-     "execution_count": 23,
+     "execution_count": 7,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -991,7 +1014,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 25,
+   "execution_count": 4,
    "metadata": {},
    "outputs": [
     {
@@ -1000,7 +1023,7 @@
        "set"
       ]
      },
-     "execution_count": 25,
+     "execution_count": 4,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1018,23 +1041,24 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 26,
+   "execution_count": 12,
    "metadata": {},
    "outputs": [
     {
-     "ename": "TypeError",
-     "evalue": "'set' object does not support indexing",
-     "output_type": "error",
-     "traceback": [
-      "\u001b[0;31m-------------------------------------------------------------------\u001b[0m",
-      "\u001b[0;31mTypeError\u001b[0m                         Traceback (most recent call last)",
-      "\u001b[0;32m<ipython-input-26-3d2453cad46e>\u001b[0m in \u001b[0;36m<module>\u001b[0;34m()\u001b[0m\n\u001b[0;32m----> 1\u001b[0;31m \u001b[0munique_travel_cities\u001b[0m\u001b[0;34m[\u001b[0m\u001b[0;36m1\u001b[0m\u001b[0;34m]\u001b[0m\u001b[0;34m\u001b[0m\u001b[0m\n\u001b[0m",
-      "\u001b[0;31mTypeError\u001b[0m: 'set' object does not support indexing"
-     ]
+     "data": {
+      "text/plain": [
+       "'Solta'"
+      ]
+     },
+     "execution_count": 12,
+     "metadata": {},
+     "output_type": "execute_result"
     }
    ],
    "source": [
-    "unique_travel_cities[1]"
+    "unique_travel_cities_list = list(unique_travel_cities)\n",
+    "\n",
+    "unique_travel_cities_list[1]"
    ]
   },
   {
@@ -1046,7 +1070,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 27,
+   "execution_count": 13,
    "metadata": {},
    "outputs": [
     {
@@ -1055,7 +1079,7 @@
        "set"
       ]
      },
-     "execution_count": 27,
+     "execution_count": 13,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1073,10 +1097,8 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 28,
-   "metadata": {
-    "collapsed": true
-   },
+   "execution_count": 14,
+   "metadata": {},
    "outputs": [],
    "source": [
     "unique_travel_cities = list(unique_travel_cities)"
@@ -1084,7 +1106,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 29,
+   "execution_count": 15,
    "metadata": {},
    "outputs": [
     {
@@ -1093,7 +1115,7 @@
        "list"
       ]
      },
-     "execution_count": 29,
+     "execution_count": 15,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1111,28 +1133,28 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 30,
+   "execution_count": 16,
    "metadata": {},
    "outputs": [
     {
      "data": {
       "text/plain": [
-       "['Toronto',\n",
+       "['Iguazu Falls',\n",
+       " 'Solta',\n",
        " 'Archipelago Sea',\n",
-       " 'Iguazu Falls',\n",
-       " 'Pyeongchang',\n",
-       " 'Los Cabos',\n",
-       " 'Buenos Aires',\n",
-       " 'Marakesh',\n",
-       " 'Greenville',\n",
+       " 'San Antonio',\n",
        " 'Albuquerque',\n",
-       " 'Salina Island',\n",
        " 'Walla Walla Valley',\n",
-       " 'San Antonio',\n",
-       " 'Solta']"
+       " 'Greenville',\n",
+       " 'Toronto',\n",
+       " 'Marakesh',\n",
+       " 'Salina Island',\n",
+       " 'Buenos Aires',\n",
+       " 'Pyeongchang',\n",
+       " 'Los Cabos']"
       ]
      },
-     "execution_count": 30,
+     "execution_count": 16,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1150,7 +1172,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 31,
+   "execution_count": 17,
    "metadata": {},
    "outputs": [
     {
@@ -1159,7 +1181,7 @@
        "13"
       ]
      },
-     "execution_count": 31,
+     "execution_count": 17,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1170,7 +1192,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 32,
+   "execution_count": 18,
    "metadata": {},
    "outputs": [
     {
@@ -1179,7 +1201,7 @@
        "14"
       ]
      },
-     "execution_count": 32,
+     "execution_count": 18,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1190,7 +1212,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 33,
+   "execution_count": 19,
    "metadata": {},
    "outputs": [
     {
@@ -1212,7 +1234,7 @@
        " 'Solta']"
       ]
      },
-     "execution_count": 33,
+     "execution_count": 19,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1254,14 +1276,14 @@
   "language_info": {
    "codemirror_mode": {
     "name": "ipython",
-    "version": 2
+    "version": 3
    },
    "file_extension": ".py",
    "mimetype": "text/x-python",
    "name": "python",
    "nbconvert_exporter": "python",
-   "pygments_lexer": "ipython2",
-   "version": "2.7.14"
+   "pygments_lexer": "ipython3",
+   "version": "3.6.6"
   }
  },
  "nbformat": 4,