Alessandro Forina developed a new C++ interface for set operations on labeled data within the metatensor/metatensor repository, focusing on the Labels::set_difference functionality. His work introduced an optional mapping feature that tracks the positions of input elements in the resulting set difference, enabling more precise differential analysis on labeled datasets. By ensuring API consistency with existing Labels operations, Alessandro improved both usability and maintainability of the codebase. The implementation leveraged his expertise in C++ development, API design, and software engineering, resulting in a robust enhancement that supports advanced data processing workflows and facilitates downstream analytics without introducing any new bugs.