BERT: Multiclass classification

Need a python implementation for BERT multiclass classification (text-category) with train-test-valid 60-20-20 and loss function as categorical cross entropy. Model to be used is: "readerbench/RoBERT-base" from huggingface (https://huggingface.co/readerbench/RoBERT-base/blob/main/README.md). Attaching dataset.