Set equal scaling (i.e., make circles circular) by
                             changing dimensions of the plot box. This is the same as
                             ``ax.set_aspect('equal', adjustable='box', anchor='C')``.
                             Additionally, further autoscaling will be disabled.
            'tight'          Set limits just large enough to show all data, then
                             disable further autoscaling.
            'auto'           Automatic scaling (fill plot box with data).
            'image'          'scaled' with axis limits equal to data limits.
            'square'         Square plot; similar to 'scaled', but initially forcing
                             ``xmax-xmin == ymax-ymin``.
            ================ ===========================================================

        emit : bool, default: True
            Whether observers are notified of the axis limit change.
            This option is passed on to `~.Axes.set_xlim` and
            `~.Axes.set_ylim`.

        Returns
        -------
        xmin, xmax, ymin, ymax : float
            The axis limits.

        See Also
        --------
        matplotlib.axes.Axes.set_xlim
        matplotlib.axes.Axes.set_ylim

        Notes
        -----
        For 3D axes, this method additionally takes *zmin*, *zmax* as
        parameters and likewise returns them.
        TZ