code: def test_null_cache(self):
      """Testing trivial NullCache: should trigger value generating function on each run"""
      cache = NullCache()
      self.assertEqual(42, cache.get("some_key", lambda: 42))
  
imports: import unittest
  from petastorm.cache import NullCache
label_desc: Use image node_id 1 for calling the TestNullCache obj's underlying member method code with example usage: obj.test_null_cache() without return types