Yusei contributed to the DefinitelyTyped/DefinitelyTyped repository by enhancing the PapaParse library’s type definitions in TypeScript. During the month, Yusei implemented a new BYTE_ORDER_MARK constant, enabling robust handling of Unicode Byte Order Marks during text parsing. This addition addressed the challenge of reliably ingesting BOM-encoded data, improving both data quality and the clarity of the library’s typings for downstream consumers. The work demonstrated a solid understanding of library development and type definition standards, focusing on practical improvements rather than broad changes. Yusei’s targeted contribution reflected depth in TypeScript and type system design, with a clear impact on library usability.