Worked on the FEniCS/dolfinx repository to improve the correctness and reliability of internal data structure representations. Focused on the AdjacencyList class, addressing an issue where its Python __repr__ method did not accurately reflect the underlying C++ object, which could lead to confusion during debugging. The solution involved updating the Python method to delegate directly to the C++ __repr__, ensuring consistency and clarity in string outputs. To prevent future regressions, a targeted unit test was added to verify the representation format. This work leveraged Python programming and unit testing skills, emphasizing careful attention to detail and maintainability.