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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 gui_repaint(self, drawDC=None):
 """ Performs update of the displayed image on the GUI canvas, using the supplied device context. If drawDC is None, a ClientDC will be used to redraw the image. """

        DEBUG_MSG("gui_repaint()", 1, self)
        if self.IsShownOnScreen():
            if drawDC is None:
                drawDC=wx.ClientDC(self)

            #drawDC.BeginDrawing()
            drawDC.DrawBitmap(self.bitmap, 0, 0)
            #drawDC.EndDrawing()
            #wx.GetApp().Yield()
        else:
            pass