docs: def unzoom(self, event=None, set_bounds=True):
          """ zoom out 1 level, or to full data range """
          lims = None
          if len(self.conf.zoom_lims) > 1:
              lims = self.conf.zoom_lims.pop()
          ax = self.axes
          if lims is None: # auto scale
              self.conf.zoom_lims = [None]
              xmin, xmax, ymin, ymax = self.data_range
              lims = {self.axes: [xmin, xmax, ymin, ymax]}
          self.set_viewlimits()
          self.canvas.draw()