def METHOD_NAME(
    self,
    retriever_mode: Union[str, DSRM] = DSRM.DEFAULT,
    **kwargs: Any,
) -> BaseRetriever:
    """Get retriever.
    Args:
        retriever_mode (Union[str, DocumentSummaryRetrieverMode]): A retriever mode.
    """
    from llama_index.indices.document_summary.retrievers import (
        DocumentSummaryIndexEmbeddingRetriever,
        DocumentSummaryIndexRetriever,
    )
    DSIR = DocumentSummaryIndexRetriever
    DSIER = DocumentSummaryIndexEmbeddingRetriever
    if retriever_mode == DSRM.DEFAULT:
        return DSIR(self, **kwargs)
    elif retriever_mode == DSRM.EMBEDDING:
        return DSIER(self, **kwargs)
    else:
        raise ValueError(f"Unknown retriever mode: {retriever_mode}")