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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 set_vertices(self, verts=None, indexed=None, reset_normals=True):
 """Set the mesh vertices Parameters verts : ndarray | None The array (Nv, 3) of vertex coordinates. indexed : str | None If indexed=='faces', then the data must have shape (Nf, 3, 3) and is assumed to be already indexed as a list of faces. This will cause any pre-existing normal vectors to be cleared unless reset_normals=False. reset_normals : bool If True, reset the normals. """

        if indexed is None:
            if verts is not None:
                self._vertices = verts
            self._vertices_indexed_by_faces = None
        elif indexed == 'faces':
            self._vertices = None
            if verts is not None:
                self._vertices_indexed_by_faces = verts
        else:
            raise Exception("Invalid indexing mode. Accepts: None, 'faces'")

        if reset_normals:
            self.reset_normals()