code: def test_key_call(self):
      key = torchbearer.state_key("call_test")
      state = {key: "test"}
  
      self.assertEqual(key(state), "test")
  
imports: import unittest
  import warnings
  import torchbearer
  from torchbearer.state import State
label_desc: Use image node_id 2 for calling the TestStateKey obj's underlying member method code with example usage: obj.test_key_call() without return types