Worked on enhancing the stability of the atcollab/at repository by addressing a critical backend issue in Python. Focused on the Lattice class, the developer resolved a crash in the deepcopy method that occurred when the _radiation attribute was uninitialized. By implementing a defensive programming approach using getattr to safely default the attribute, they eliminated the risk of AttributeError and ensured robust object copying. Additionally, they introduced a regression test to verify the fix and improve test coverage. This work strengthened the reliability of core data structures and supported more dependable simulations, leveraging skills in Python, backend development, and unit testing.