The base class
PreTrainedModel implements the common methods for loading/saving a model either from a local file or directory, or from a pretrained model configuration provided by the library (downloaded from HuggingFace’s AWS S3 repository).
PreTrainedModel also implements a few methods which are common among all the models to:
resize the input token embeddings when new tokens are added to the vocabulary
prune the attention heads of the model.