----------
        angles : tuple with floats, degrees
            The angles of the theta gridlines.

        labels : tuple with strings or None
            The labels to use at each theta gridline. The
            `.projections.polar.ThetaFormatter` will be used if None.

        fmt : str or None
            Format string used in `matplotlib.ticker.FormatStrFormatter`.
            For example '%f'. Note that the angle that is used is in
            radians.

        Returns
        -------
        lines : list of `.lines.Line2D`
            The theta gridlines.

        labels : list of `.text.Text`
            The tick labels.

        Other Parameters
        ----------------
        **kwargs
            *kwargs* are optional `.Text` properties for the labels.

        See Also
        --------
        .PolarAxes.set_rgrids
        .Axis.get_gridlines
        .Axis.get_ticklabels
        )