def testRepeatedLabels(self):
    # Repeated indices.
    self._check_gradient('aba,a->b', (3, 4, 3), (3,))
    self._check_gradient('ijj,k->ik', (2, 3, 3), (4,))
    self._check_gradient('ill,k->ik', (2, 3, 3), (4,))