Ondra Polacek contributed to the pola-rs/polars repository by refining the type hints for the Series.quantile method in the Python API. Focusing on developer experience and type safety, Ondra updated the type annotations to better reflect the intended API behavior, which helps reduce type-related errors for downstream users. This work clarified the API contract, making it easier for both contributors and users to understand and use the quantile method correctly. The changes were implemented using Python and leveraged type hinting expertise, resulting in improved code readability and onboarding for new developers. The contribution was targeted and technically precise in scope.