add *pad_points* of padding (in points) between the axis and the
            label.  The x-direction is in axis coordinates and the y-direction
            is in data coordinates
        valign : {'center', 'top', 'bottom', 'baseline', 'center_baseline'}
            The text vertical alignment.
        halign : {'center', 'left', 'right'}
            The text horizontal alignment.

        Notes
        -----
        This transformation is primarily used by the `~matplotlib.axis.Axis`
        class, and is meant to be overridden by new kinds of projections that
        may need to place axis elements in different locations.
        rS