src/transformers/models/rag/retrieval_rag.py/CustomHFIndex/init_index
class CustomHFIndex:    def init_index(self):
        if not self.is_initialized():
            logger.info(f"Loading index from {self.index_path}")
            self.dataset.load_faiss_index("embeddings", file=self.index_path)
            self._index_initialized = True