<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def viewbox_mouse_event(self, event):
 """ The ViewBox received a mouse event; update transform accordingly. Default implementation adjusts scale factor when scolling. Parameters event : instance of Event The event. """

        BaseCamera.viewbox_mouse_event(self, event)
        if event.type == 'mouse_wheel':
            s = 1.1 ** - event.delta[1]
            self._scale_factor *= s
            if self._distance is not None:
                self._distance *= s
            self.view_changed()