sub nummering: a, b, c

Please replace all _____ before you create a pull request!

Start the name of the PR with one of the relevant prefixes in the title of the PR:

• 🖊️ -> changes related to grammars or the transpiler
• 🪲 -> solving a bug
• 🚚 -> changes unrelated to shipping, such as mergify scripts
• 🧹 -> refactorings (changes that do not change functionality and are only a cleanup of code)
• 💻 -> improvements and changes of the Hedy website
• 🧪 -> changes made to the test suite
• 📜 -> changes related to content

Fixes _______ (Always link the number of the issue or of the discussion that your PR concerns. If you use the word fixes before the issue number in this description, the related issue will automatically close then the PR is merged)

How to test

Follow these steps to verify this PR works as intended:

• _____ (See this Stop long running programs in client-side JS #880 (comment) for an example)

• ---

Checklist
Done? Check if you have it all in place using this list: (mark with x if done)

• Contains one of the PR categories in the name
• Describes changes in the format above
• Links to an existing issue or discussion
• Has a "How to test" section

If you're unsure about any of these, don't hesitate to ask. We're here to help!