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Solve the following problem using Python, implementing the functions described below, one line at a time
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Description:
 def _convert_agg_to_wx_image(agg, bbox):
 """ Convert the region of the agg buffer bounded by bbox to a wx.Image. If bbox is None, the entire buffer is converted. Note: agg must be a backend_agg.RendererAgg instance. """

    if bbox is None:
        # agg => rgb -> image
        image = wx.EmptyImage(int(agg.width), int(agg.height))
        image.SetData(agg.tostring_rgb())
        return image
    else:
        # agg => rgba buffer -> bitmap => clipped bitmap => image
        return wx.ImageFromBitmap(_WX28_clipped_agg_as_bitmap(agg, bbox))