If `data = dict(a=1)`, what happens when `del data["b"]` runs?
It raises `KeyError`.✓Bonne réponse
It leaves the dictionary unchanged without an exception.
It inserts `b` with value `None`.
It clears the entire dictionary.
Explication
Deletion by key requires an existing entry, and this dictionary has no key `b`, so Python raises `KeyError`. The operation is not silently ignored and does not create a key whose value is `None`.