Alessandro Forina developed a new C++ interface for set operations on labeled data in the metatensor/metatensor repository, focusing on the Labels::set_difference functionality. He designed the API to allow optional mapping, enabling users to track the positions of input elements in the resulting set difference, which supports more precise differential analysis on labeled datasets. The implementation emphasized consistency with existing Labels operations, improving both usability and maintainability. Using C++ and applying principles of API design and software engineering, Alessandro’s work enhanced the Labels class, facilitating more robust data processing workflows and supporting downstream analytics without introducing bugs during the development period.