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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 face_adjacency_radius(self):
 """ The approximate radius of a cylinder that fits inside adjacent faces. Returns radii : (len(self.face_adjacency),) float Approximate radius formed by triangle pair """

        radii, span = graph.face_adjacency_radius(mesh=self)
        self._cache['face_adjacency_span'] = span
        return radii