code: def test_flatten_empty():
      val = (
          npr.randn(4),
          [npr.randn(3, 4), 2.5],
          (),
          (2.0, [1.0, npr.randn(2)]),
      )
      vect, unflatten = flatten(val)
      val_recovered = unflatten(vect)
      vect_2, _ = flatten(val_recovered)
      assert np.all(vect == vect_2)
  
file_path: autograd/tests/test_misc.py
imports: import autograd.numpy
  import autograd.numpy.random
  from autograd.test_util import scalar_close
  from autograd import make_vjp, grad
  from autograd.tracer import primitive
  from autograd.misc import const_graph, flatten
label_desc: Use image node_id 4 for calling a global function with example usage: test_flatten_empty() without return types