Worked on the huggingface/trl repository to enhance the developer experience by updating documentation for the training processing_class parameter across several trainer classes. Focused on clarifying expected types and default values, the changes aimed to align documentation with actual API behavior, reducing configuration errors during model training. Used Python and technical writing skills to ensure the guidance accurately reflected the codebase, supporting more reliable training setups. No bugs were fixed during this period, but the work laid a foundation for upcoming API changes and improved onboarding. The updates are intended to reduce support queries and streamline the user configuration process.