PEP-604 (landed in Python 3.10) introduced a new short syntax for typing.Union (as I predicted, but I messed up union with intersection, shame on me): def greet(name: str) -> str | None: if not name: return None return f"Hello, {name}" You already can use it in older Python versions by adding from __future__ import annotations, type checkers will understand you. 5.5K views14:01