langchain/vectorstores/chroma.py/Chroma/__query_collection
class Chroma:    def __query_collection(
        self,
        query_texts: Optional[List[str]] = None,
        query_embeddings: Optional[List[List[float]]] = None,
        n_results: int = 4,
        where: Optional[Dict[str, str]] = None,
        **kwargs: Any,
    ) -> List[Document]:
        """Query the chroma collection."""
        try:
            import chromadb
        except ImportError:
            raise ValueError(
                "Could not import chromadb python package. "
                "Please install it with `pip install chromadb`."
            )

        for i in range(n_results, 0, -1):
            try:
                return self._collection.query(
                    query_texts=query_texts,
                    query_embeddings=query_embeddings,
                    n_results=i,
                    where=where,
                    **kwargs,
                )
            except chromadb.errors.NotEnoughElementsException:
                logger.error(
                    f"Chroma collection {self._collection.name} "
                    f"contains fewer than {i} elements."
                )
        raise chromadb.errors.NotEnoughElementsException(
            f"No documents found for Chroma collection {self._collection.name}"
        )