Ensure to format Python code after tangling

README.org

@@ -2560,19 +2560,29 @@ Listing [[lst:configure-writegood-mode]] configures [[https://github.com/bnbeckw
 :CUSTOM_ID: sec:format-all
 :END:
 
-Listing [[lst:configure-format-all]] configures [[https://github.com/lassik/emacs-format-all-the-code#readme][format-all]] which is a package that
-provides an universal interface to code formatters of more than 60 computer
-languages.
+Listing [[lst:configure-format-all]]:
+1. Configures [[https://github.com/lassik/emacs-format-all-the-code#readme][format-all]] which is a package that provides an universal interface
+   to code formatters of more than 60 computer languages.
+2. Adds =format-all-org-babel-post-tangle= to =org-babel-post-tangle-hook= to
+   format tangled Python code.
 
 #+caption[Configure =format-all=]:
 #+caption: Configure =format-all=.
 #+name: lst:configure-format-all
 #+begin_src emacs-lisp
-  ;; https://ianyepan.github.io/posts/format-all/
   ;; https://github.com/lassik/emacs-format-all-the-code#readme
+  ;; https://ianyepan.github.io/posts/format-all/
+  ;; https://jamesaimonetti.com/posts/formatting-tangled-output-in-org-mode/
   (when (ensure-package-installation 'format-all)
     (when (fboundp 'format-all-ensure-formatter)
-      (add-hook 'prog-mode-hook #'format-all-ensure-formatter)))
+      (add-hook 'prog-mode-hook #'format-all-ensure-formatter))
+
+    (add-hook 'org-babel-post-tangle-hook
+              (defun format-all-org-babel-post-tangle ()
+                (when (derived-mode-p 'python-mode)
+                  (let ((format-all-formatters '(("Python" black))))
+                    (message "Format whole `%s' buffer after tangling" major-mode)
+                    (format-all-buffer))))))
 #+end_src
 
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