langchain/retrievers/time_weighted_retriever.py/TimeWeightedVectorStoreRetriever/get_relevant_documents
class TimeWeightedVectorStoreRetriever:    def get_relevant_documents(self, query: str) -> List[Document]:
        """Return documents that are relevant to the query."""
        current_time = datetime.datetime.now()
        docs_and_scores = {
            doc.metadata["buffer_idx"]: (doc, self.default_salience)
            for doc in self.memory_stream[-self.k :]
        }
        # If a doc is considered salient, update the salience score
        docs_and_scores.update(self.get_salient_docs(query))
        rescored_docs = [
            (doc, self._get_combined_score(doc, relevance, current_time))
            for doc, relevance in docs_and_scores.values()
        ]
        rescored_docs.sort(key=lambda x: x[1], reverse=True)
        result = []
        # Ensure frequently accessed memories aren't forgotten
        for doc, _ in rescored_docs[: self.k]:
            # TODO: Update vector store doc once `update` method is exposed.
            buffered_doc = self.memory_stream[doc.metadata["buffer_idx"]]
            buffered_doc.metadata["last_accessed_at"] = current_time
            result.append(buffered_doc)
        return result