old_contents: import unittest
  
  from rdbtools import RdbParser
  from rdbtools import MemoryCallback
  import os
  
  class Stats():
      def __init__(self):
          self.records = {}
          
      def next_record(self, record):
          self.records[record.key] = record
  
  def get_stats(file_name):
      stats = Stats()
      callback = MemoryCallback(stats, 64)
      parser = RdbParser(callback)
      parser.parse(os.path.join(os.path.dirname(__file__), 'dumps', file_name))
      return stats.records
      
  class MemoryCallbackTestCase(unittest.TestCase):
      def setUp(self):
          pass
  
      def test_len_largest_element(self):
          stats = get_stats('ziplist_that_compresses_easily.rdb')
          self.assertEqual(stats['ziplist_compresses_easily'].len_largest_element, 36, "Length of largest element does not match")
          
      
new_contents: import unittest
  
  from rdbtools import RdbParser
  from rdbtools import MemoryCallback
  import os
  
  class Stats(object):
      def __init__(self):
          self.records = {}
          
      def next_record(self, record):
          self.records[record.key] = record
  
  def get_stats(file_name):
      stats = Stats()
      callback = MemoryCallback(stats, 64)
      parser = RdbParser(callback)
      parser.parse(os.path.join(os.path.dirname(__file__), 'dumps', file_name))
      return stats.records
      
  class MemoryCallbackTestCase(unittest.TestCase):
      def setUp(self):
          pass
  
      def test_len_largest_element(self):
          stats = get_stats('ziplist_that_compresses_easily.rdb')
          self.assertEqual(stats['ziplist_compresses_easily'].len_largest_element, 36, "Length of largest element does not match")
  
  
subject: add missing object inheritance