old_contents: from __future__ import with_statement
  import os
  import pickle
  from contextlib import closing
  try:
      from redis import Redis
  except ImportError:
      Redis = None
  
  
  class Cache(object):
      def __init__(self):
          self._cache = {}
  
      def get(self, k):
          return self._cache.get(k)
  
      def set(self, k, v):
          self._cache[k] = v
  
  
  class PickleCache(Cache):
      def __init__(self, filename='cache.db'):
          self.filename = filename
          self._cache = self.load()
      
      def load(self):
          if os.path.exists(self.filename):
              with closing(open(self.filename)) as fh:
                  contents = fh.read()
              return pickle.loads(contents)
          return {}
  
      def save(self):
          with closing(open(self.filename, 'w')) as fh:
              fh.write(pickle.dumps(self._cache))
  
  
  if Redis:
      class RedisCache(Cache):
          def __init__(self, namespace='micawber', **conn):
              self.namespace = namespace
              self.key_fn = lambda self, k: '%s.%s' % (self.namespace, k)
              self.conn = Redis(**conn)
          
          def get(self, k):
              cached = self.conn.get(self.key_fn(k))
              if cached:
                  return pickle.loads(cached)
          
          def set(self, k, v):
              self.conn.set(self.key_fn(k), pickle.dumps(v))
  
new_contents: from __future__ import with_statement
  import os
  import pickle
  from contextlib import closing
  try:
      from redis import Redis
  except ImportError:
      Redis = None
  
  
  class Cache(object):
      def __init__(self):
          self._cache = {}
  
      def get(self, k):
          return self._cache.get(k)
  
      def set(self, k, v):
          self._cache[k] = v
  
  
  class PickleCache(Cache):
      def __init__(self, filename='cache.db'):
          self.filename = filename
          self._cache = self.load()
      
      def load(self):
          if os.path.exists(self.filename):
              with closing(open(self.filename, 'rb')) as fh:
                  return pickle.load(fh)
          return {}
  
      def save(self):
          with closing(open(self.filename, 'wb')) as fh:
              pickle.dump(self._cache, fh)
  
  
  if Redis:
      class RedisCache(Cache):
          def __init__(self, namespace='micawber', **conn):
              self.namespace = namespace
              self.key_fn = lambda self, k: '%s.%s' % (self.namespace, k)
              self.conn = Redis(**conn)
          
          def get(self, k):
              cached = self.conn.get(self.key_fn(k))
              if cached:
                  return pickle.loads(cached)
          
          def set(self, k, v):
              self.conn.set(self.key_fn(k), pickle.dumps(v))
  
subject: Fix PicleCache error on Python3