langchain/vectorstores/tair.py/Tair/drop_index
class Tair:    def drop_index(
        index_name: str = "langchain",
        **kwargs: Any,
    ) -> bool:
        """
        Drop an existing index.

        Args:
            index_name (str): Name of the index to drop.

        Returns:
            bool: True if the index is dropped successfully.
        """
        try:
            from tair import Tair as TairClient
        except ImportError:
            raise ValueError(
                "Could not import tair python package. "
                "Please install it with `pip install tair`."
            )
        url = get_from_dict_or_env(kwargs, "tair_url", "TAIR_URL")

        try:
            if "tair_url" in kwargs:
                kwargs.pop("tair_url")
            client = TairClient.from_url(url=url, **kwargs)
        except ValueError as e:
            raise ValueError(f"Tair connection error: {e}")
        # delete index
        ret = client.tvs_del_index(index_name)
        if ret == 0:
            # index not exist
            logger.info("Index does not exist")
            return False
        return True