class_docstr: Fake environment with non-zero observations.
class_docstr_tok: ["Fake","environment","with","non-zero","observations","."]
code: def _generate_fake_observation(self):
      original_observation = super()._generate_fake_observation()
      return tree.map_structure(np.ones_like, original_observation)
  
file_path: acme/acme/wrappers/frame_stacking_test.py
imports: from acme import wrappers
  from acme.testing import fakes
  import numpy
  import tree
  from absl.testing import absltest
label_desc: Use image node_id 1 for calling the FakeNonZeroObservationEnvironment obj's underlying member method code with example usage: obj._generate_fake_observation() and returns: tree