During February 2026, this developer refactored the FrozenTrial module in the optuna/optuna repository to improve code readability and correctness. By migrating string formatting from the older .format method to modern Python f-strings, they enhanced maintainability and reduced the risk of formatting-related bugs. The work involved careful code refactoring and Python programming, with attention to detail that surfaced and resolved a minor regression introduced during the process. Their contribution focused on aligning the codebase with ongoing quality standards, resulting in a more robust and consistent FrozenTrial representation that will lower future maintenance costs and streamline ongoing development efforts.