diff --git a/docs/beta/404.html b/docs/beta/404.html
index e5f1b8a5..39204620 100644
--- a/docs/beta/404.html
+++ b/docs/beta/404.html
@@ -12038,7 +12038,7 @@
 <div class="cell border-box-sizing text_cell rendered">
 <div class="inner_cell">
 <div class="text_cell_render border-box-sizing rendered_html"><h2 id="Getting-Informed-About-New-Content">Getting Informed About New Content<a class="anchor-link" href="#Getting-Informed-About-New-Content">&#182;</a></h2><p>New chapters are coming out every week.  To get notified when a new chapter (or this one) comes out, <a href="https://mastodon.social/invite/P27cijZH">follow us on Mastodon</a>.</p>
-<iframe allowfullscreen sandbox="allow-top-navigation allow-scripts allow-popups allow-popups-to-escape-sandbox" width="400" height="400" src="https://mastofeed.com/apiv2/feed?userurl=https%3A%2F%2Fmastodon.social%2Fusers%2FTheDebuggingBook&theme=auto&size=100&header=false&replies=false&boosts=false"></iframe></div>
+<iframe allowfullscreen sandbox="allow-top-navigation allow-scripts allow-popups allow-popups-to-escape-sandbox" width="400" height="400" frameBorder="0" src="https://mastofeed.com/apiv2/feed?userurl=https%3A%2F%2Fmastodon.social%2Fusers%2FTheDebuggingBook&theme=auto&size=100&header=false&replies=false&boosts=false"></iframe></div>
 </div>
 </div>
 </div>
@@ -12105,7 +12105,7 @@
 
 <div class="output_subarea output_stream output_stderr output_text">
 <pre>Traceback (most recent call last):
-  File &#34;/var/folders/n2/xd9445p97rb3xh7m1dfx8_4h0006ts/T/ipykernel_24902/1830731544.py&#34;, line 4, in &lt;cell line: 3&gt;
+  File &#34;/var/folders/n2/xd9445p97rb3xh7m1dfx8_4h0006ts/T/ipykernel_36148/1830731544.py&#34;, line 4, in &lt;cell line: 3&gt;
     raise NotFoundError
 NotFoundError: &#39;404&#39; (expected)
 </pre>
@@ -12119,7 +12119,7 @@
 The content of this project is licensed under the
 <a href="https://creativecommons.org/licenses/by-nc-sa/4.0/" target=_blank>Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License</a>.
 The source code that is part of the content, as well as the source code used to format and display that content is licensed under the <a href="https://github.com/uds-se/debuggingbook/blob/master/LICENSE.md#mit-license">MIT License</a>.
-<a href="https://github.com/uds-se/debuggingbook/commits/master/notebooks/404.ipynb" target=_blank)>Last change: 2023-10-24 12:43:51+02:00</a> &bull; 
+<a href="https://github.com/uds-se/debuggingbook/commits/master/notebooks/404.ipynb" target=_blank)>Last change: 2023-10-24 12:46:55+02:00</a> &bull; 
 <a href="#citation" id="cite" onclick="revealCitation()">Cite</a> &bull;
 <a href="https://cispa.de/en/impressum" target=_blank>Imprint</a>
 </p>
@@ -12135,7 +12135,7 @@
 <a name="citation"></a>
 <h2>How to Cite this Work</h2>
 <p>
-Andreas Zeller: "<a href="https://www.debuggingbook.org/beta/">The Debugging Book</a>".  Retrieved 2023-10-24 12:43:51+02:00.
+Andreas Zeller: "<a href="https://www.debuggingbook.org/beta/">The Debugging Book</a>".  Retrieved 2023-10-24 12:46:55+02:00.
 </p>
 <pre>
 @book{debuggingbook2023,
@@ -12144,9 +12144,9 @@ <h2>How to Cite this Work</h2>
     year = {2023},
     publisher = {CISPA Helmholtz Center for Information Security},
     howpublished = {\url{https://www.debuggingbook.org/beta/}},
-    note = {Retrieved 2023-10-24 12:43:51+02:00},
+    note = {Retrieved 2023-10-24 12:46:55+02:00},
     url = {https://www.debuggingbook.org/beta/},
-    urldate = {2023-10-24 12:43:51+02:00}
+    urldate = {2023-10-24 12:46:55+02:00}
 }
 </pre>
 </div>
diff --git a/docs/beta/dist/debuggingbook-1.1.2.tar.gz b/docs/beta/dist/debuggingbook-1.1.2.tar.gz
index 7cf29da7..4371a304 100644
Binary files a/docs/beta/dist/debuggingbook-1.1.2.tar.gz and b/docs/beta/dist/debuggingbook-1.1.2.tar.gz differ
diff --git a/docs/beta/dist/debuggingbook-code.zip b/docs/beta/dist/debuggingbook-code.zip
index 8611fa90..29397d9f 100644
Binary files a/docs/beta/dist/debuggingbook-code.zip and b/docs/beta/dist/debuggingbook-code.zip differ
diff --git a/docs/beta/dist/debuggingbook-notebooks.zip b/docs/beta/dist/debuggingbook-notebooks.zip
index eeae666a..ea9bc91a 100644
Binary files a/docs/beta/dist/debuggingbook-notebooks.zip and b/docs/beta/dist/debuggingbook-notebooks.zip differ
diff --git a/docs/beta/html/404.html b/docs/beta/html/404.html
index b8f208ce..2e2241ea 100644
--- a/docs/beta/html/404.html
+++ b/docs/beta/html/404.html
@@ -12040,7 +12040,7 @@
 <div class="cell border-box-sizing text_cell rendered">
 <div class="inner_cell">
 <div class="text_cell_render border-box-sizing rendered_html"><h2 id="Getting-Informed-About-New-Content">Getting Informed About New Content<a class="anchor-link" href="#Getting-Informed-About-New-Content">&#182;</a></h2><p>New chapters are coming out every week.  To get notified when a new chapter (or this one) comes out, <a href="https://mastodon.social/invite/P27cijZH">follow us on Mastodon</a>.</p>
-<iframe allowfullscreen sandbox="allow-top-navigation allow-scripts allow-popups allow-popups-to-escape-sandbox" width="400" height="400" src="https://mastofeed.com/apiv2/feed?userurl=https%3A%2F%2Fmastodon.social%2Fusers%2FTheDebuggingBook&theme=auto&size=100&header=false&replies=false&boosts=false"></iframe></div>
+<iframe allowfullscreen sandbox="allow-top-navigation allow-scripts allow-popups allow-popups-to-escape-sandbox" width="400" height="400" frameBorder="0" src="https://mastofeed.com/apiv2/feed?userurl=https%3A%2F%2Fmastodon.social%2Fusers%2FTheDebuggingBook&theme=auto&size=100&header=false&replies=false&boosts=false"></iframe></div>
 </div>
 </div>
 </div>
@@ -12107,7 +12107,7 @@
 
 <div class="output_subarea output_stream output_stderr output_text">
 <pre>Traceback (most recent call last):
-  File &#34;/var/folders/n2/xd9445p97rb3xh7m1dfx8_4h0006ts/T/ipykernel_24902/1830731544.py&#34;, line 4, in &lt;cell line: 3&gt;
+  File &#34;/var/folders/n2/xd9445p97rb3xh7m1dfx8_4h0006ts/T/ipykernel_36148/1830731544.py&#34;, line 4, in &lt;cell line: 3&gt;
     raise NotFoundError
 NotFoundError: &#39;404&#39; (expected)
 </pre>
@@ -12121,7 +12121,7 @@
 The content of this project is licensed under the
 <a href="https://creativecommons.org/licenses/by-nc-sa/4.0/" target=_blank>Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License</a>.
 The source code that is part of the content, as well as the source code used to format and display that content is licensed under the <a href="https://github.com/uds-se/debuggingbook/blob/master/LICENSE.md#mit-license">MIT License</a>.
-<a href="https://github.com/uds-se/debuggingbook/commits/master/notebooks/404.ipynb" target=_blank)>Last change: 2023-10-24 12:43:51+02:00</a> &bull; 
+<a href="https://github.com/uds-se/debuggingbook/commits/master/notebooks/404.ipynb" target=_blank)>Last change: 2023-10-24 12:46:55+02:00</a> &bull; 
 <a href="#citation" id="cite" onclick="revealCitation()">Cite</a> &bull;
 <a href="https://cispa.de/en/impressum" target=_blank>Imprint</a>
 </p>
@@ -12137,7 +12137,7 @@
 <a name="citation"></a>
 <h2>How to Cite this Work</h2>
 <p>
-Andreas Zeller: "<a href="https://www.debuggingbook.org/beta/html/404.html">Oh, no!  We are not ready yet!</a>".  In Andreas Zeller, "<a href="https://www.debuggingbook.org/beta/">The Debugging Book</a>", <a href="https://www.debuggingbook.org/beta/html/404.html">https://www.debuggingbook.org/beta/html/404.html</a>.  Retrieved 2023-10-24 12:43:51+02:00.
+Andreas Zeller: "<a href="https://www.debuggingbook.org/beta/html/404.html">Oh, no!  We are not ready yet!</a>".  In Andreas Zeller, "<a href="https://www.debuggingbook.org/beta/">The Debugging Book</a>", <a href="https://www.debuggingbook.org/beta/html/404.html">https://www.debuggingbook.org/beta/html/404.html</a>.  Retrieved 2023-10-24 12:46:55+02:00.
 </p>
 <pre>
 @incollection{debuggingbook2023:404,
@@ -12147,9 +12147,9 @@ <h2>How to Cite this Work</h2>
     year = {2023},
     publisher = {CISPA Helmholtz Center for Information Security},
     howpublished = {\url{https://www.debuggingbook.org/beta/html/404.html}},
-    note = {Retrieved 2023-10-24 12:43:51+02:00},
+    note = {Retrieved 2023-10-24 12:46:55+02:00},
     url = {https://www.debuggingbook.org/beta/html/404.html},
-    urldate = {2023-10-24 12:43:51+02:00}
+    urldate = {2023-10-24 12:46:55+02:00}
 }
 </pre>
 </div>
diff --git a/docs/beta/html/index.html b/docs/beta/html/index.html
index 1710e394..3cde8998 100644
--- a/docs/beta/html/index.html
+++ b/docs/beta/html/index.html
@@ -12053,7 +12053,7 @@
 <div class="cell border-box-sizing text_cell rendered">
 <div class="inner_cell">
 <div class="text_cell_render border-box-sizing rendered_html"><h2 id="News">News<a class="anchor-link" href="#News">&#182;</a></h2><p>This book is <em>work in progress</em>, with new chapters being released every week. To get notified on updates, <a href="https://mastodon.social/invite/P27cijZH">follow us on Mastodon</a>.</p>
-<iframe allowfullscreen sandbox="allow-top-navigation allow-scripts allow-popups allow-popups-to-escape-sandbox" width="400" height="400" src="https://mastofeed.com/apiv2/feed?userurl=https%3A%2F%2Fmastodon.social%2Fusers%2FTheDebuggingBook&theme=auto&size=100&header=false&replies=false&boosts=false"></iframe></div>
+<iframe allowfullscreen sandbox="allow-top-navigation allow-scripts allow-popups allow-popups-to-escape-sandbox" width="400" height="400" frameBorder="0" src="https://mastofeed.com/apiv2/feed?userurl=https%3A%2F%2Fmastodon.social%2Fusers%2FTheDebuggingBook&theme=auto&size=100&header=false&replies=false&boosts=false"></iframe></div>
 </div>
 </div>
 </div>
@@ -12339,7 +12339,7 @@
 The content of this project is licensed under the
 <a href="https://creativecommons.org/licenses/by-nc-sa/4.0/" target=_blank>Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License</a>.
 The source code that is part of the content, as well as the source code used to format and display that content is licensed under the <a href="https://github.com/uds-se/debuggingbook/blob/master/LICENSE.md#mit-license">MIT License</a>.
-<a href="https://github.com/uds-se/debuggingbook/commits/master/notebooks/index.ipynb" target=_blank)>Last change: 2023-10-24 12:43:15+02:00</a> &bull; 
+<a href="https://github.com/uds-se/debuggingbook/commits/master/notebooks/index.ipynb" target=_blank)>Last change: 2023-10-24 12:46:51+02:00</a> &bull; 
 <a href="#citation" id="cite" onclick="revealCitation()">Cite</a> &bull;
 <a href="https://cispa.de/en/impressum" target=_blank>Imprint</a>
 </p>
@@ -12355,7 +12355,7 @@
 <a name="citation"></a>
 <h2>How to Cite this Work</h2>
 <p>
-Andreas Zeller: "<a href="https://www.debuggingbook.org/beta/html/index.html">About this Book</a>".  In Andreas Zeller, "<a href="https://www.debuggingbook.org/beta/">The Debugging Book</a>", <a href="https://www.debuggingbook.org/beta/html/index.html">https://www.debuggingbook.org/beta/html/index.html</a>.  Retrieved 2023-10-24 12:43:15+02:00.
+Andreas Zeller: "<a href="https://www.debuggingbook.org/beta/html/index.html">About this Book</a>".  In Andreas Zeller, "<a href="https://www.debuggingbook.org/beta/">The Debugging Book</a>", <a href="https://www.debuggingbook.org/beta/html/index.html">https://www.debuggingbook.org/beta/html/index.html</a>.  Retrieved 2023-10-24 12:46:51+02:00.
 </p>
 <pre>
 @incollection{debuggingbook2023:index,
@@ -12365,9 +12365,9 @@ <h2>How to Cite this Work</h2>
     year = {2023},
     publisher = {CISPA Helmholtz Center for Information Security},
     howpublished = {\url{https://www.debuggingbook.org/beta/html/index.html}},
-    note = {Retrieved 2023-10-24 12:43:15+02:00},
+    note = {Retrieved 2023-10-24 12:46:51+02:00},
     url = {https://www.debuggingbook.org/beta/html/index.html},
-    urldate = {2023-10-24 12:43:15+02:00}
+    urldate = {2023-10-24 12:46:51+02:00}
 }
 </pre>
 </div>
diff --git a/docs/beta/index.html b/docs/beta/index.html
index 0fee346c..395ecc09 100644
--- a/docs/beta/index.html
+++ b/docs/beta/index.html
@@ -12048,7 +12048,7 @@
 <div class="cell border-box-sizing text_cell rendered">
 <div class="inner_cell">
 <div class="text_cell_render border-box-sizing rendered_html"><h2 id="News">News<a class="anchor-link" href="#News">&#182;</a></h2><p>This book is <em>work in progress</em>, with new chapters being released every week. To get notified on updates, <a href="https://mastodon.social/invite/P27cijZH">follow us on Mastodon</a>.</p>
-<iframe allowfullscreen sandbox="allow-top-navigation allow-scripts allow-popups allow-popups-to-escape-sandbox" width="400" height="400" src="https://mastofeed.com/apiv2/feed?userurl=https%3A%2F%2Fmastodon.social%2Fusers%2FTheDebuggingBook&theme=auto&size=100&header=false&replies=false&boosts=false"></iframe></div>
+<iframe allowfullscreen sandbox="allow-top-navigation allow-scripts allow-popups allow-popups-to-escape-sandbox" width="400" height="400" frameBorder="0" src="https://mastofeed.com/apiv2/feed?userurl=https%3A%2F%2Fmastodon.social%2Fusers%2FTheDebuggingBook&theme=auto&size=100&header=false&replies=false&boosts=false"></iframe></div>
 </div>
 </div>
 </div>
@@ -12334,7 +12334,7 @@
 The content of this project is licensed under the
 <a href="https://creativecommons.org/licenses/by-nc-sa/4.0/" target=_blank>Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License</a>.
 The source code that is part of the content, as well as the source code used to format and display that content is licensed under the <a href="https://github.com/uds-se/debuggingbook/blob/master/LICENSE.md#mit-license">MIT License</a>.
-<a href="https://github.com/uds-se/debuggingbook/commits/master/notebooks/index.ipynb" target=_blank)>Last change: 2023-10-24 12:43:15+02:00</a> &bull; 
+<a href="https://github.com/uds-se/debuggingbook/commits/master/notebooks/index.ipynb" target=_blank)>Last change: 2023-10-24 12:46:51+02:00</a> &bull; 
 <a href="#citation" id="cite" onclick="revealCitation()">Cite</a> &bull;
 <a href="https://cispa.de/en/impressum" target=_blank>Imprint</a>
 </p>
@@ -12350,7 +12350,7 @@
 <a name="citation"></a>
 <h2>How to Cite this Work</h2>
 <p>
-Andreas Zeller: "<a href="https://www.debuggingbook.org/beta/">The Debugging Book</a>".  Retrieved 2023-10-24 12:43:15+02:00.
+Andreas Zeller: "<a href="https://www.debuggingbook.org/beta/">The Debugging Book</a>".  Retrieved 2023-10-24 12:46:51+02:00.
 </p>
 <pre>
 @book{debuggingbook2023,
@@ -12359,9 +12359,9 @@ <h2>How to Cite this Work</h2>
     year = {2023},
     publisher = {CISPA Helmholtz Center for Information Security},
     howpublished = {\url{https://www.debuggingbook.org/beta/}},
-    note = {Retrieved 2023-10-24 12:43:15+02:00},
+    note = {Retrieved 2023-10-24 12:46:51+02:00},
     url = {https://www.debuggingbook.org/beta/},
-    urldate = {2023-10-24 12:43:15+02:00}
+    urldate = {2023-10-24 12:46:51+02:00}
 }
 </pre>
 </div>
diff --git a/docs/beta/notebooks/404.ipynb b/docs/beta/notebooks/404.ipynb
index a7d5f2a3..8323877e 100644
--- a/docs/beta/notebooks/404.ipynb
+++ b/docs/beta/notebooks/404.ipynb
@@ -74,7 +74,7 @@
     "\n",
     "New chapters are coming out every week.  To get notified when a new chapter (or this one) comes out, <a href=\"https://mastodon.social/invite/P27cijZH\">follow us on Mastodon</a>.\n",
     "\n",
-    "<iframe allowfullscreen sandbox=\"allow-top-navigation allow-scripts allow-popups allow-popups-to-escape-sandbox\" width=\"400\" height=\"400\" src=\"https://mastofeed.com/apiv2/feed?userurl=https%3A%2F%2Fmastodon.social%2Fusers%2FTheDebuggingBook&theme=auto&size=100&header=false&replies=false&boosts=false\"></iframe>"
+    "<iframe allowfullscreen sandbox=\"allow-top-navigation allow-scripts allow-popups allow-popups-to-escape-sandbox\" width=\"400\" height=\"400\" frameBorder=\"0\" src=\"https://mastofeed.com/apiv2/feed?userurl=https%3A%2F%2Fmastodon.social%2Fusers%2FTheDebuggingBook&theme=auto&size=100&header=false&replies=false&boosts=false\"></iframe>"
    ]
   },
   {
@@ -93,10 +93,10 @@
    "execution_count": 1,
    "metadata": {
     "execution": {
-     "iopub.execute_input": "2023-10-24T10:45:05.676623Z",
-     "iopub.status.busy": "2023-10-24T10:45:05.676502Z",
-     "iopub.status.idle": "2023-10-24T10:45:05.712288Z",
-     "shell.execute_reply": "2023-10-24T10:45:05.711940Z"
+     "iopub.execute_input": "2023-10-24T10:47:35.288708Z",
+     "iopub.status.busy": "2023-10-24T10:47:35.288558Z",
+     "iopub.status.idle": "2023-10-24T10:47:35.330360Z",
+     "shell.execute_reply": "2023-10-24T10:47:35.329951Z"
     },
     "slideshow": {
      "slide_type": "skip"
@@ -112,10 +112,10 @@
    "execution_count": 2,
    "metadata": {
     "execution": {
-     "iopub.execute_input": "2023-10-24T10:45:05.714636Z",
-     "iopub.status.busy": "2023-10-24T10:45:05.714246Z",
-     "iopub.status.idle": "2023-10-24T10:45:05.716568Z",
-     "shell.execute_reply": "2023-10-24T10:45:05.716247Z"
+     "iopub.execute_input": "2023-10-24T10:47:35.333349Z",
+     "iopub.status.busy": "2023-10-24T10:47:35.332972Z",
+     "iopub.status.idle": "2023-10-24T10:47:35.335969Z",
+     "shell.execute_reply": "2023-10-24T10:47:35.335496Z"
     },
     "slideshow": {
      "slide_type": "fragment"
@@ -136,10 +136,10 @@
    "execution_count": 3,
    "metadata": {
     "execution": {
-     "iopub.execute_input": "2023-10-24T10:45:05.718278Z",
-     "iopub.status.busy": "2023-10-24T10:45:05.718160Z",
-     "iopub.status.idle": "2023-10-24T10:45:05.748923Z",
-     "shell.execute_reply": "2023-10-24T10:45:05.748616Z"
+     "iopub.execute_input": "2023-10-24T10:47:35.338627Z",
+     "iopub.status.busy": "2023-10-24T10:47:35.338496Z",
+     "iopub.status.idle": "2023-10-24T10:47:35.369548Z",
+     "shell.execute_reply": "2023-10-24T10:47:35.369187Z"
     },
     "slideshow": {
      "slide_type": "skip"
@@ -151,7 +151,7 @@
      "output_type": "stream",
      "text": [
       "Traceback (most recent call last):\n",
-      "  File \"/var/folders/n2/xd9445p97rb3xh7m1dfx8_4h0006ts/T/ipykernel_24902/1830731544.py\", line 4, in <cell line: 3>\n",
+      "  File \"/var/folders/n2/xd9445p97rb3xh7m1dfx8_4h0006ts/T/ipykernel_36148/1830731544.py\", line 4, in <cell line: 3>\n",
       "    raise NotFoundError\n",
       "NotFoundError: '404' (expected)\n"
      ]
diff --git a/docs/beta/notebooks/index.ipynb b/docs/beta/notebooks/index.ipynb
index 7b3db448..e1fbef7e 100644
--- a/docs/beta/notebooks/index.ipynb
+++ b/docs/beta/notebooks/index.ipynb
@@ -24,10 +24,10 @@
    "execution_count": 1,
    "metadata": {
     "execution": {
-     "iopub.execute_input": "2023-10-24T10:45:01.409529Z",
-     "iopub.status.busy": "2023-10-24T10:45:01.409425Z",
-     "iopub.status.idle": "2023-10-24T10:45:01.452698Z",
-     "shell.execute_reply": "2023-10-24T10:45:01.452382Z"
+     "iopub.execute_input": "2023-10-24T10:47:31.899300Z",
+     "iopub.status.busy": "2023-10-24T10:47:31.899172Z",
+     "iopub.status.idle": "2023-10-24T10:47:31.946559Z",
+     "shell.execute_reply": "2023-10-24T10:47:31.946087Z"
     },
     "slideshow": {
      "slide_type": "skip"
@@ -49,7 +49,7 @@
        "        "
       ],
       "text/plain": [
-       "<IPython.lib.display.IFrame at 0x1057f5d50>"
+       "<IPython.lib.display.IFrame at 0x1087f5600>"
       ]
      },
      "execution_count": 1,
@@ -108,7 +108,7 @@
     "\n",
     "This book is _work in progress_, with new chapters being released every week. To get notified on updates, <a href=\"https://mastodon.social/invite/P27cijZH\">follow us on Mastodon</a>.\n",
     "\n",
-    "<iframe allowfullscreen sandbox=\"allow-top-navigation allow-scripts allow-popups allow-popups-to-escape-sandbox\" width=\"400\" height=\"400\" src=\"https://mastofeed.com/apiv2/feed?userurl=https%3A%2F%2Fmastodon.social%2Fusers%2FTheDebuggingBook&theme=auto&size=100&header=false&replies=false&boosts=false\"></iframe>"
+    "<iframe allowfullscreen sandbox=\"allow-top-navigation allow-scripts allow-popups allow-popups-to-escape-sandbox\" width=\"400\" height=\"400\" frameBorder=\"0\" src=\"https://mastofeed.com/apiv2/feed?userurl=https%3A%2F%2Fmastodon.social%2Fusers%2FTheDebuggingBook&theme=auto&size=100&header=false&replies=false&boosts=false\"></iframe>"
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