old_contents: import asyncio
  import http.cookies
  
  from aiohttp import hdrs, CIMultiDict
  
  from .abc import AbstractIdentityPolicy
  
  
  sentinel = object()
  
  
  class CookiesIdentityPolicy(AbstractIdentityPolicy):
  
      def __init__(self):
          self._cookie_name = 'AIOHTTP_SECURITY'
          self._max_age = 30 * 24 * 3600
  
      @asyncio.coroutine
      def identify(self, request):
          identity = request.cookies.get(self._cookie_name)
          return identity
  
      @asyncio.coroutine
      def remember(self, request, response, identity, max_age=sentinel,
                   **kwargs):
          if max_age is sentinel:
              max_age = self._max_age
          response.set_cookie(self._cookie_name, max_age=max_age, **kwargs)
  
      @asyncio.coroutine
      def forget(self, request, response):
          response.del_cookie(self._cookie_name)
  
new_contents: import asyncio
  
  from .abc import AbstractIdentityPolicy
  
  
  sentinel = object()
  
  
  class CookiesIdentityPolicy(AbstractIdentityPolicy):
  
      def __init__(self):
          self._cookie_name = 'AIOHTTP_SECURITY'
          self._max_age = 30 * 24 * 3600
  
      @asyncio.coroutine
      def identify(self, request):
          identity = request.cookies.get(self._cookie_name)
          return identity
  
      @asyncio.coroutine
      def remember(self, request, response, identity, max_age=sentinel,
                   **kwargs):
          if max_age is sentinel:
              max_age = self._max_age
          response.set_cookie(self._cookie_name, max_age=max_age, **kwargs)
  
      @asyncio.coroutine
      def forget(self, request, response):
          response.del_cookie(self._cookie_name)
  
subject: Drop unused imports