GoKawiilPython 3.15 adds built-in 'sentinel' type to fix None's ambiguity problem
A talk on sentinel values, presented at PyConDE/PyData Berlin, EuroPython and the Swiss Python Summit in 2026, examines how Python's None is overused to mean missing, unset, error, or a real value, causing bugs when these meanings collide. The talk notes that PEP 661, a proposal to standardize sentinel objects, was deferred in April but accepted by the Steering Council just nine days later, and Python 3.15 now ships a built-in 'sentinel' construct that static type checkers can narrow properly.