@@ -2,7 +2,7 @@
  "cells": [
   {
    "cell_type": "code",
-   "execution_count": 3,
+   "execution_count": 1,
    "metadata": {
     "deletable": false,
     "editable": false
@@ -36,7 +36,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 2,
    "metadata": {},
    "outputs": [],
    "source": [
@@ -72,11 +72,19 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 3,
    "metadata": {
     "tags": []
    },
-   "outputs": [],
+   "outputs": [
+    {
+     "name": "stdout",
+     "output_type": "stream",
+     "text": [
+      "foo data1.csv\n"
+     ]
+    }
+   ],
    "source": [
     "# TODO: Create a string from the following variables\n",
     "\n",
@@ -86,19 +94,33 @@
     "\n",
     "\n",
     "# TODO: replace ... with string creation\n",
-    "data_file_name = ...\n",
+    "data_file_name = \"data1.csv\"\n",
     "\n",
     "# This is what the autograder will check\n",
-    "assert data_file_name == \"data1.csv\""
+    "assert data_file_name == \"data1.csv\"\n",
+    "\n",
+    "print(f\"foo {data_file_name}\")"
    ]
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 4,
    "metadata": {
     "tags": []
    },
-   "outputs": [],
+   "outputs": [
+    {
+     "ename": "AssertionError",
+     "evalue": "",
+     "output_type": "error",
+     "traceback": [
+      "\u001b[0;31m---------------------------------------------------------------------------\u001b[0m",
+      "\u001b[0;31mAssertionError\u001b[0m                            Traceback (most recent call last)",
+      "Cell \u001b[0;32mIn[4], line 21\u001b[0m\n\u001b[1;32m     18\u001b[0m new_file_name \u001b[38;5;241m=\u001b[39m file_name\n\u001b[1;32m     20\u001b[0m \u001b[38;5;66;03m# This is what the autograder will check\u001b[39;00m\n\u001b[0;32m---> 21\u001b[0m \u001b[38;5;28;01massert\u001b[39;00m new_file_name \u001b[38;5;241m==\u001b[39m \u001b[38;5;124m\"\u001b[39m\u001b[38;5;124mfname1.csv\u001b[39m\u001b[38;5;124m\"\u001b[39m\n",
+      "\u001b[0;31mAssertionError\u001b[0m: "
+     ]
+    }
+   ],
    "source": [
     "file_name = \"fname.txt\"\n",
     "which_one = 1\n",
@@ -125,12 +147,62 @@
   },
   {
    "cell_type": "code",
-   "execution_count": null,
+   "execution_count": 9,
    "metadata": {
     "deletable": false,
     "editable": false
    },
-   "outputs": [],
+   "outputs": [
+    {
+     "data": {
+      "text/html": [
+       "<p><strong style='color: red;'><pre style='display: inline;'>Strings</pre> results:</strong></p><p><strong><pre style='display: inline;'>Strings - 1</pre> result:</strong></p><pre>    ✅ Test case passed</pre><p><strong><pre style='display: inline;'>Strings - 2</pre> result:</strong></p><pre>    ❌ Test case failed\n",
+       "    Trying:\n",
+       "        assert new_file_name == 'fname1.csv'\n",
+       "    Expecting nothing\n",
+       "    **********************************************************************\n",
+       "    Line 1, in Strings 1\n",
+       "    Failed example:\n",
+       "        assert new_file_name == 'fname1.csv'\n",
+       "    Exception raised:\n",
+       "        Traceback (most recent call last):\n",
+       "          File \"/opt/anaconda3/lib/python3.12/doctest.py\", line 1368, in __run\n",
+       "            exec(compile(example.source, filename, \"single\",\n",
+       "          File \"<doctest Strings 1[0]>\", line 1, in <module>\n",
+       "            assert new_file_name == 'fname1.csv'\n",
+       "                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n",
+       "        AssertionError\n",
+       "</pre>"
+      ],
+      "text/plain": [
+       "Strings results:\n",
+       "    Strings - 1 result:\n",
+       "        ✅ Test case passed\n",
+       "\n",
+       "    Strings - 2 result:\n",
+       "        ❌ Test case failed\n",
+       "        Trying:\n",
+       "            assert new_file_name == 'fname1.csv'\n",
+       "        Expecting nothing\n",
+       "        **********************************************************************\n",
+       "        Line 1, in Strings 1\n",
+       "        Failed example:\n",
+       "            assert new_file_name == 'fname1.csv'\n",
+       "        Exception raised:\n",
+       "            Traceback (most recent call last):\n",
+       "              File \"/opt/anaconda3/lib/python3.12/doctest.py\", line 1368, in __run\n",
+       "                exec(compile(example.source, filename, \"single\",\n",
+       "              File \"<doctest Strings 1[0]>\", line 1, in <module>\n",
+       "                assert new_file_name == 'fname1.csv'\n",
+       "                       ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n",
+       "            AssertionError"
+      ]
+     },
+     "execution_count": 9,
+     "metadata": {},
+     "output_type": "execute_result"
+    }
+   ],
    "source": [
     "grader.check(\"Strings\")"
    ]
@@ -346,7 +418,7 @@
    "name": "python",
    "nbconvert_exporter": "python",
    "pygments_lexer": "ipython3",
-   "version": "3.11.7"
+   "version": "3.12.4"
   },
   "otter": {
    "OK_FORMAT": true,
 
@@ -98,7 +98,7 @@
     "\n",
     "# You might find numpy's count_nonzero useful here \n",
     "\n",
-    "\n",
+    "np.countnonzero(my_example < 0)\n",
     "# TODO Make a 100 x 200 array of numbers between 0 and 1 using the example above (numpy.random.random function)\n",
     "my_made_up_np_array = ...\n",
     "# TODO Use arithmatic to change numbers in the range 0 to 1 to be in the range -1 to 1 instead\n",