langchain/chains/qa_with_sources/vector_db.py/VectorDBQAWithSourcesChain/_get_docs
class VectorDBQAWithSourcesChain:    def _get_docs(self, inputs: Dict[str, Any]) -> List[Document]:
        question = inputs[self.question_key]
        docs = self.vectorstore.similarity_search(
            question, k=self.k, **self.search_kwargs
        )
        return self._reduce_tokens_below_limit(docs)