old_contents: from __future__ import unicode_literals
  
  import time
  
  
  class Cache(object):
  
      def __init__(self, cache_time):
          self._cache = {}
          self._cache_time = cache_time
  
      def __repr__(self):
          return 'Cache(cache_time={})'.format(self._cache_time)
  
      def _cache_valid(self, key):
          return (key in self._cache and
                  self._cache[key]['access_time'] >
                  time.time() - self._cache_time)
  
      def get(self, key):
          if self._cache_valid(key):
              return self._cache[key]['obj']
          else:
              return False
  
      def insert(self, key, obj):
          if self._cache_time:
              self._cache[key] = {
                  'access_time': time.time(),
                  'obj': obj
              }
  
new_contents: from __future__ import unicode_literals
  
  import time
  
  
  class Cache(object):
  
      def __init__(self, cache_time):
          self._cache = {}
          self._cache_time = cache_time
  
      def __repr__(self):
          return 'Cache(cache_time={})'.format(self._cache_time)
  
      def _cache_valid(self, key):
          return (key in self._cache and
                  self._cache[key]['access_time'] >
                  time.time() - self._cache_time)
  
      def get(self, key):
          if self._cache_valid(key):
              return self._cache[key]['obj']
          else:
              return None
  
      def insert(self, key, obj):
          if self._cache_time:
              self._cache[key] = {
                  'access_time': time.time(),
                  'obj': obj
              }
  
subject: Return None from cache if not found