code: def test_no_key(self):
      packer = UnpackState()
      state = self.reset_state()
  
      packer.on_sample(state)
      self.assertTrue(state[torchbearer.X] == "data")
  
      state = self.reset_state()
      packer.on_sample_validation(state)
      self.assertTrue(state[torchbearer.X] == "data")
  
file_path: torchbearer/tests/callbacks/test_unpack_state.py
imports: import torch
  from unittest import TestCase
  from mock import MagicMock, patch
  import torchbearer
  from torchbearer.callbacks import UnpackState
label_desc: Use image node_id 3 for calling the TestUnpackState obj's underlying member method code with example usage: obj.test_no_key() without return types