def zoom_out(self, decr=1.0):
        """Zoom out a level.
        Also see :meth:`zoom_to`.

        Parameters
        ----------
        decr : float (optional, defaults to 1)
            The value to decrease the zoom level

        """
        level = self.zoom.calc_level(self.t_['scale'])
        self.zoom_to(level - decr)
Zoom out a level.
        Also see :meth:`zoom_to`.

        Parameters
        ----------
        decr : float (optional, defaults to 1)
            The value to decrease the zoom level