old_contents: """uWSGI cache backend"""
  
  from django.core.cache.backends.base import BaseCache, InvalidCacheBackendError
  from django.utils.encoding import smart_str
  from django.conf import settings
  
  try:
      import cPickle as pickle
  except ImportError:
      import pickle
  
  try:
      import uwsgi
  except:
      if getattr(settings, "UWSGI_CACHE_FALLBACK", True):
          uwsgi = None
      else:
          raise InvalidCacheBackendError(
              "You're not running under uWSGI ! "
              "Set UWSGI_CACHE_FALLBACK=True in settings if you want to fallback "
              "to LocMemCache."
          )
  
  if uwsgi:
      class UWSGICache(BaseCache):
          def __init__(self, server, params):
              BaseCache.__init__(self, params)
              self._cache = uwsgi
              self._server = server
  
          def exists(self, key):
              return self._cache.cache_exists(smart_str(key), self._server)
  
          def add(self, key, value, timeout=0):
              if self.exists(key):
                  return False
              return self.set(key, value, timeout, self._server)
  
          def get(self, key, default=None):
              val = self._cache.cache_get(smart_str(key), self._server)
              if val is None:
                  return default
              val = smart_str(val)
              return pickle.loads(val)
  
          def set(self, key, value, timeout=0):
              self._cache.cache_update(smart_str(key), pickle.dumps(value), timeout, self._server)
  
          def delete(self, key):
              self._cache.cache_del(smart_str(key), self._server)
  
          def close(self, **kwargs):
              pass
  
          def clear(self):
              pass
  else:
      from django.core.cache.backends.locmem import LocMemCache as UWSGICache
      from django.core.cache.backends import locmem
  
  class CacheClass(UWSGICache):
      pass
  
new_contents: """uWSGI cache backend"""
  
  from django.core.cache.backends.base import BaseCache, InvalidCacheBackendError
  from django.utils.encoding import smart_str
  from django.conf import settings
  
  try:
      import cPickle as pickle
  except ImportError:
      import pickle
  
  try:
      import uwsgi
  except:
      if getattr(settings, "UWSGI_CACHE_FALLBACK", True):
          uwsgi = None
      else:
          raise InvalidCacheBackendError(
              "You're not running under uWSGI ! "
              "Set UWSGI_CACHE_FALLBACK=True in settings if you want to fallback "
              "to LocMemCache."
          )
  
  if uwsgi:
      class UWSGICache(BaseCache):
          def __init__(self, server, params):
              BaseCache.__init__(self, params)
              self._cache = uwsgi
              self._server = server
  
          def exists(self, key):
              return self._cache.cache_exists(smart_str(key), self._server)
  
          def add(self, key, value, timeout=0, version=None):
              key = self.make_key(key, version=version)
              if self.exists(key):
                  return False
              return self.set(key, value, timeout, self._server)
  
          def get(self, key, default=None, version=None):
              key = self.make_key(key, version=version)
              val = self._cache.cache_get(smart_str(key), self._server)
              if val is None:
                  return default
              val = smart_str(val)
              return pickle.loads(val)
  
          def set(self, key, value, timeout=0, version=None):
              key = self.make_key(key, version=version)
              self._cache.cache_update(smart_str(key), pickle.dumps(value), timeout, self._server)
  
          def delete(self, key, version=None):
              key = self.make_key(key, version=version)
              self._cache.cache_del(smart_str(key), self._server)
  
          def close(self, **kwargs):
              pass
  
          def clear(self):
              pass
  else:
      from django.core.cache.backends.locmem import LocMemCache as UWSGICache
      from django.core.cache.backends import locmem
  
  class CacheClass(UWSGICache):
      pass
  
subject: Add support for cache versioning