During December 2025, Iuyo focused on improving the NVIDIA/Megatron-LM repository by addressing a bug related to legacy tokenizer assignment. Using Python and leveraging skills in data preprocessing and machine learning, Iuyo modified the codebase to ensure that the Encoder.tokenizer is correctly set based on the legacy flag. This adjustment prevents misassignment of tokenizers, which could otherwise lead to errors during model training or inference. The solution involved directly assigning the appropriate tokenizer in legacy mode, maintaining compatibility across different code paths. Iuyo validated the fix with targeted checks, ensuring robust behavior and reducing the risk of tokenizer-related issues.