Worked on the potiuk/airflow repository to stabilize the handling of the ArgNotSet sentinel, focusing on improving determinism and reliability across data pipelines. Developed a stable string representation and enhanced serialization logic for ArgNotSet, ensuring consistent behavior regardless of environment or runtime. Leveraged Python for backend development and implemented comprehensive unit tests to verify that serialization and string representation remained robust and reproducible. Adjusted the __repr__ and __str__ methods to delegate to a unified serialization function, which improved logging and debugging clarity. Expanded test coverage to guard against regressions, contributing to the maintainability and reliability of ArgNotSet-related features.