During August 2025, J. Tran enhanced the Flatten transform in the anthropics/beam repository to improve data pipeline reliability. By introducing strict input type checking using Python, Tran ensured that only valid PCollections could be passed to the Flatten operation, preventing incorrect flattening when users supplied iterables containing PCollections. This update addressed a subtle bug that could have led to silent data corruption in Apache Beam data processing workflows. Tran also developed a dedicated unit test to verify the new error condition, leveraging skills in type checking and data processing to reduce debugging time and guard against future regressions in the codebase.