diff --git a/code/10/series.ipynb b/code/10/series.ipynb
index 62ae025..fb365f2 100644
--- a/code/10/series.ipynb
+++ b/code/10/series.ipynb
@@ -14,7 +14,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 148,
+   "execution_count": 1,
    "metadata": {
     "collapsed": true
    },
@@ -41,7 +41,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 149,
+   "execution_count": 2,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -63,7 +63,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 150,
+   "execution_count": 3,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -105,7 +105,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 151,
+   "execution_count": 4,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -124,7 +124,7 @@
        "Name: numbers, dtype: int64"
       ]
      },
-     "execution_count": 151,
+     "execution_count": 4,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -143,7 +143,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 152,
+   "execution_count": 5,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -157,7 +157,7 @@
        "RangeIndex(start=0, stop=100, step=1)"
       ]
      },
-     "execution_count": 152,
+     "execution_count": 5,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -168,7 +168,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 153,
+   "execution_count": 6,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -190,7 +190,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 154,
+   "execution_count": 7,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -204,7 +204,7 @@
        "dtype('int64')"
       ]
      },
-     "execution_count": 154,
+     "execution_count": 7,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -215,7 +215,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 155,
+   "execution_count": 8,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -229,7 +229,7 @@
        "(100,)"
       ]
      },
-     "execution_count": 155,
+     "execution_count": 8,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -240,7 +240,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 156,
+   "execution_count": 9,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -254,7 +254,7 @@
        "100"
       ]
      },
-     "execution_count": 156,
+     "execution_count": 9,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -265,7 +265,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 157,
+   "execution_count": 10,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -279,7 +279,7 @@
        "'numbers'"
       ]
      },
-     "execution_count": 157,
+     "execution_count": 10,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -290,7 +290,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 158,
+   "execution_count": 11,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -309,7 +309,7 @@
        "        5, 31, 23, 25,  9, 41, 29, 23, 20, 39, 48, 47,  9, 14, 32])"
       ]
      },
-     "execution_count": 158,
+     "execution_count": 11,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -332,7 +332,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 159,
+   "execution_count": 12,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -354,7 +354,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 160,
+   "execution_count": 13,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -379,7 +379,7 @@
        "Length: 100, dtype: int64"
       ]
      },
-     "execution_count": 160,
+     "execution_count": 13,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -390,7 +390,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 161,
+   "execution_count": 14,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -415,7 +415,7 @@
        "Length: 100, dtype: int64"
       ]
      },
-     "execution_count": 161,
+     "execution_count": 14,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -426,7 +426,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 162,
+   "execution_count": 15,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -451,7 +451,7 @@
        "Length: 100, dtype: int64"
       ]
      },
-     "execution_count": 162,
+     "execution_count": 15,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -462,7 +462,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 163,
+   "execution_count": 16,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -487,7 +487,7 @@
        "Length: 100, dtype: float64"
       ]
      },
-     "execution_count": 163,
+     "execution_count": 16,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -498,7 +498,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 164,
+   "execution_count": 17,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -512,7 +512,7 @@
        "49"
       ]
      },
-     "execution_count": 164,
+     "execution_count": 17,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -523,7 +523,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 165,
+   "execution_count": 18,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -537,7 +537,7 @@
        "1"
       ]
      },
-     "execution_count": 165,
+     "execution_count": 18,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -548,7 +548,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 166,
+   "execution_count": 19,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -562,7 +562,7 @@
        "25.5"
       ]
      },
-     "execution_count": 166,
+     "execution_count": 19,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -573,7 +573,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 167,
+   "execution_count": 20,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -587,7 +587,7 @@
        "25.51"
       ]
      },
-     "execution_count": 167,
+     "execution_count": 20,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -598,7 +598,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 168,
+   "execution_count": 21,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -612,7 +612,7 @@
        "14.990566056926294"
       ]
      },
-     "execution_count": 168,
+     "execution_count": 21,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -630,7 +630,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 169,
+   "execution_count": 22,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -649,7 +649,7 @@
        "Name: numbers, dtype: bool"
       ]
      },
-     "execution_count": 169,
+     "execution_count": 22,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -667,7 +667,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 170,
+   "execution_count": 23,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -686,7 +686,7 @@
        "Name: numbers, dtype: int64"
       ]
      },
-     "execution_count": 170,
+     "execution_count": 23,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -697,7 +697,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 171,
+   "execution_count": 24,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -716,7 +716,7 @@
        "Name: numbers, dtype: bool"
       ]
      },
-     "execution_count": 171,
+     "execution_count": 24,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -728,7 +728,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 172,
+   "execution_count": 25,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -747,7 +747,7 @@
        "Name: numbers, dtype: int64"
       ]
      },
-     "execution_count": 172,
+     "execution_count": 25,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -770,7 +770,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 173,
+   "execution_count": 26,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -784,7 +784,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 174,
+   "execution_count": 27,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -802,7 +802,7 @@
        "Name: fruit, dtype: int64"
       ]
      },
-     "execution_count": 174,
+     "execution_count": 27,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -813,7 +813,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 175,
+   "execution_count": 28,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -831,7 +831,7 @@
        "Name: fruit, dtype: int64"
       ]
      },
-     "execution_count": 175,
+     "execution_count": 28,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -842,7 +842,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 176,
+   "execution_count": 29,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -850,6 +850,14 @@
     }
    },
    "outputs": [
+    {
+     "name": "stderr",
+     "output_type": "stream",
+     "text": [
+      "/var/folders/0t/s0c95rbs6ds7w_b0d471p0kc0000gn/T/ipykernel_83159/772644344.py:1: FutureWarning: The default value of regex will change from True to False in a future version.\n",
+      "  str_series.str.replace(\"[p]{2}\", \"XX\")\n"
+     ]
+    },
     {
      "data": {
       "text/plain": [
@@ -860,7 +868,7 @@
        "Name: fruit, dtype: object"
       ]
      },
-     "execution_count": 176,
+     "execution_count": 29,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -871,7 +879,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 177,
+   "execution_count": 30,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -880,13 +888,13 @@
    },
    "outputs": [],
    "source": [
-    "dt_series = pd.Series([20220101, 20220201, 20220301, 20220401], name=\"date\")\n",
+    "dt_series = pd.Series([20220101, 20220201, 20220301, 20220401], name=\"date\").astype(\"string\")\n",
     "dt_series = pd.to_datetime(dt_series, format=\"%Y-%m-%d\")"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": 178,
+   "execution_count": 31,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -900,7 +908,7 @@
        "dtype('<M8[ns]')"
       ]
      },
-     "execution_count": 178,
+     "execution_count": 31,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -911,7 +919,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 179,
+   "execution_count": 32,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -922,14 +930,14 @@
     {
      "data": {
       "text/plain": [
-       "0   1970-01-01 00:00:00.020220101\n",
-       "1   1970-01-01 00:00:00.020220201\n",
-       "2   1970-01-01 00:00:00.020220301\n",
-       "3   1970-01-01 00:00:00.020220401\n",
+       "0   2022-01-01\n",
+       "1   2022-02-01\n",
+       "2   2022-03-01\n",
+       "3   2022-04-01\n",
        "Name: date, dtype: datetime64[ns]"
       ]
      },
-     "execution_count": 179,
+     "execution_count": 32,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -940,7 +948,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 180,
+   "execution_count": 33,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -952,13 +960,13 @@
      "data": {
       "text/plain": [
        "0    1\n",
-       "1    1\n",
-       "2    1\n",
-       "3    1\n",
+       "1    2\n",
+       "2    3\n",
+       "3    4\n",
        "Name: date, dtype: int64"
       ]
      },
-     "execution_count": 180,
+     "execution_count": 33,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -969,7 +977,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 181,
+   "execution_count": 34,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -980,14 +988,14 @@
     {
      "data": {
       "text/plain": [
-       "0    1\n",
-       "1    1\n",
-       "2    1\n",
-       "3    1\n",
+       "0     1\n",
+       "1    32\n",
+       "2    60\n",
+       "3    91\n",
        "Name: date, dtype: int64"
       ]
      },
-     "execution_count": 181,
+     "execution_count": 34,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -998,7 +1006,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 182,
+   "execution_count": 35,
    "metadata": {
     "collapsed": false,
     "pycharm": {
@@ -1009,14 +1017,14 @@
     {
      "data": {
       "text/plain": [
-       "0    3\n",
-       "1    3\n",
-       "2    3\n",
-       "3    3\n",
+       "0    5\n",
+       "1    1\n",
+       "2    1\n",
+       "3    4\n",
        "Name: date, dtype: int64"
       ]
      },
-     "execution_count": 182,
+     "execution_count": 35,
      "metadata": {},
      "output_type": "execute_result"
     }
@@ -1028,21 +1036,26 @@
  ],
  "metadata": {
   "kernelspec": {
-   "display_name": "Python 3",
+   "display_name": "Python 3.10.4 ('sspai-100-hours-series-python')",
    "language": "python",
    "name": "python3"
   },
   "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": "2.7.6"
+   "pygments_lexer": "ipython3",
+   "version": "3.10.4"
+  },
+  "vscode": {
+   "interpreter": {
+    "hash": "7a101baf08afe636412f97dd4a9fc2e65b6f84f0ec50413bf3e19b04a26b8ba6"
+   }
   }
  },
  "nbformat": 4,