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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 _shade_missing_label(self):
 """Helper method to shade a missing label. Not intended for external use. """

        # Start a drawing for the whole label.
        label = Drawing(float(self._lw), float(self._lh))
        label.add(self._clip_label)

        # Fill with a rectangle; the clipping path will take care of the borders.
        r = shapes.Rect(0, 0, float(self._lw), float(self._lh))
        r.fillColor = self.shade_missing
        r.strokeColor = None
        label.add(r)

        # Add the label to the page.
        label.shift(*self._calculate_edges())
        self._current_page.add(label)