def rindex(
        self,
        sub: str | bytes | Any,
        start: int | Any = 0,
        end: int | Any = None,
    ) -> T_DataArray:
        """
        Return highest indexes in each strings where the substring is
        fully contained between [start:end]. This is the same as
        ``str.rfind`` except instead of returning -1, it raises a ValueError
        when the substring is not found.

        If `start`, `end`, or 'sub` is array-like, they are broadcast
        against the array and applied elementwise.

        Parameters
        ----------
        sub : str or array-like of str
            Substring being searched.
            If array-like, it is broadcast.
        start : int or array-like of int
            Left edge index.
            If array-like, it is broadcast.
        end : int or array-like of int
            Right edge index.
            If array-like, it is broadcast.

        Returns
        -------
        found : array of int

        Raises
        ------
        ValueError
            substring is not found
        """
        return self.index(sub, start=start, end=end, side="right")

        Return highest indexes in each strings where the substring is
        fully contained between [start:end]. This is the same as
        ``str.rfind`` except instead of returning -1, it raises a ValueError
        when the substring is not found.

        If `start`, `end`, or 'sub` is array-like, they are broadcast
        against the array and applied elementwise.

        Parameters
        ----------
        sub : str or array-like of str
            Substring being searched.
            If array-like, it is broadcast.
        start : int or array-like of int
            Left edge index.
            If array-like, it is broadcast.
        end : int or array-like of int
            Right edge index.
            If array-like, it is broadcast.

        Returns
        -------
        found : array of int

        Raises
        ------
        ValueError
            substring is not found
        
xarray/core/accessor_str.py