src/transformers/models/rag/retrieval_rag.py/LegacyIndex/init_index
class LegacyIndex:    def init_index(self):
        index = faiss.IndexHNSWFlat(self.vector_size + 1, 512)
        index.hnsw.efSearch = 128
        index.hnsw.efConstruction = 200
        self.index = index
        self._deserialize_index()
        self._index_initialized = True