Worked on the python/typeshed repository to enhance type safety and flexibility for Pynput event callback APIs. Focused on refining Python type annotations to support callbacks with varying argument counts, such as handling both on_click() and on_click(x, y) signatures, and clarified return semantics to distinguish between bool and None. This targeted API development improved the usability and predictability of event iteration, enabling safer stopping mechanisms for downstream integrations. By applying precise annotation fixes, the work strengthened maintainability and consistency within the codebase. The approach demonstrated a strong command of Python and type annotations, addressing nuanced requirements in API design.