pytype.pytd.optimize.AbsorbMutableParameters

Converts mutable parameters to unions. This is lossy. For example, this will change def f(x: list[int]): x = list[Union[int, float]] to def f(x: Union[list[int], list[Union[int, float]]) . (Use optimize.CombineContainers to then change x to list[Union[int, float]].) This also works for methods - it will then potentially change the type of "self". The resulting AST is temporary and needs careful handling.