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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 smoothed(self, angle=.4):
 """ Return a version of the current mesh which will render nicely, without changing source mesh. Parameters angle : float Angle in radians, face pairs with angles smaller than this value will appear smoothed Returns --------- smoothed : trimesh.Trimesh Non watertight version of current mesh which will render nicely with smooth shading """


        # smooth should be recomputed if visuals change
        self.visual._verify_crc()
        cached = self.visual._cache['smoothed']
        if cached is not None:
            return cached

        smoothed = graph.smoothed(self, angle)
        self.visual._cache['smoothed'] = smoothed
        return smoothed