TypeError: '_TypedDict' object is not subscriptable
You can't subscript TypedDict; you're meant to instantiate or subclass one according to the docs: Point2D = TypedDict('Point2D', x=int, y=int, label=str) Point2D = TypedDict('Point2D', {'x': int, 'y': int, 'label': str}) With that in mind, you can just inline that in your signature: def x(a: TypedDict('A', x=int)): pass
