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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 flip_normals(self):
 """ Flip normals of a triangular mesh by reversing the point ordering. """

        if self.faces.size % 4:
            raise Exception('Can only flip normals on an all triangular mesh')

        f = self.faces.reshape((-1, 4))
        f[:, 1:] = f[:, 1:][:, ::-1]