code: def on_mouse_wheel(self, event):
          '''handle mouse wheel zoom changes'''
          rotation = event.GetWheelRotation() / event.GetWheelDelta()
          if rotation > 0:
              zoom = 1.0/(1.1 * rotation)
          elif rotation < 0:
              zoom = 1.1 * (-rotation)
          self.change_zoom(zoom)
          self.redraw_map(f on_mouse_wheel(self, event):
          '''handle mouse wheel zoom changes'''
          rotation = event.GetWheelRotation() / event.GetWheelDelta()
          if rotation > 0:
              zoom = 1.0/(1.1 * rotation)
          elif rotation < 0:
              zoom = 1.1 * (-rotation)
          self.change_zoom(zoom)
          self.redraw_map()
docs: handle mouse wheel zoom changes