rder to flip the direction of
        the y-axis. For example, suppose ``y`` represents depth of the
        ocean in m. The y-axis limits might be set like the following
        so 5000 m depth is at the bottom of the plot and the surface,
        0 m, is at the top.

        >>> set_ylim(5000, 0)
        Nz$Cannot pass both 'bottom' and 'ymin'z!Cannot pass both 'top' and 'ymax'rv