langchain/vectorstores/sklearn.py/SKLearnVectorStore/_update_neighbors
class SKLearnVectorStore:    def _update_neighbors(self) -> None:
        if len(self._embeddings) == 0:
            raise SKLearnVectorStoreException(
                "No data was added to SKLearnVectorStore."
            )
        self._embeddings_np = self._np.asarray(self._embeddings)
        self._neighbors.fit(self._embeddings_np)
        self._neighbors_fitted = True