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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_bitmap(agg, bbox):
 """ Convert the region of the agg buffer bounded by bbox to a wx.Bitmap. If bbox is None, the entire buffer is converted. Note: agg must be a backend_agg.RendererAgg instance. """

    if bbox is None:
        # agg => rgba buffer -> bitmap
        return wx.BitmapFromBufferRGBA(int(agg.width), int(agg.height),
            agg.buffer_rgba())
    else:
        # agg => rgba buffer -> bitmap => clipped bitmap
        return _WX28_clipped_agg_as_bitmap(agg, bbox)