code: def test_stack_plus_minus(self, shape, result_shape):
      @partial(jnp.vectorize, signature="()->(n)")
      def stack_plus_minus(x):
          return jnp.stack([x, -x])
  
      self.assertEqual(
          stack_plus_minus(jnp.zeros(shape)).shape, result_shape
      )
  
imports: from functools import partial
  from absl.testing import absltest
  import numpy
  import jax
  from jax import numpy
  from jax._src import test_util
  from jax import config
label_desc: Use image node_id 6 for calling the VectorizeTest obj's underlying member method code with example usage: obj.test_stack_plus_minus(shape, result_shape) and returns: jnp