code: def test_flatten_nd_out_negative(self):
      mod = reshape.Flatten(preserve_dims=-2)
      x = jnp.zeros([5, 2, 3])
      y = mod(x)
      self.assertEqual(y.shape, (5, 6))
  
imports: import unittest
  from absl.testing import absltest
  from absl.testing import parameterized
  from haiku._src import reshape
  from haiku._src import test_utils
  from haiku._src import transform
  import jax
  from jax.experimental import jax2tf
  import jax.numpy
  import numpy
label_desc: Use image node_id 9 for calling the ReshapeTest obj's underlying member method code with example usage: obj.test_flatten_nd_out_negative() without return types