old_contents: import redis
  
  """ Cache is a set with information already seen by the system.
      This provides a way, for example, to remove duplicated events
      and reports in system or cache some results from experts like
      Cymru Whois. It's possible to define a TTL value in each information
      inserted in cache. This TTL means how much time the system will keep an 
      information in the cache.
  """
  
  class Cache():
      def __init__(self, host, port, db, ttl):
          self.redis = redis.Redis(host = host,
                                   port = int(port),
                                   db = db,
                                   socket_timeout = 5)
          
          self.ttl = ttl
  
  
      def exists(self, key):
          return self.redis.exists(key)
  
      def get(self, key):
          return self.redis.get(key)
  
      def set(self, key, value):
          # backward compatibility (Redis v2.2)
          self.redis.setnx(key, value)
          self.redis.expire(key, self.ttl)
  
new_contents: import redis
  
  """ Cache is a set with information already seen by the system.
      This provides a way, for example, to remove duplicated events
      and reports in system or cache some results from experts like
      Cymru Whois. It's possible to define a TTL value in each information
      inserted in cache. This TTL means how much time the system will keep an
      information in the cache.
  """
  
  
  class Cache():
      def __init__(self, host, port, db, ttl):
          self.redis = redis.Redis(host=host,
                                   port=int(port),
                                   db=db,
                                   socket_timeout=5)
  
          self.ttl = ttl
  
      def exists(self, key):
          """Returns True if key exists in the cache"""
          return self.redis.exists(key)
  
      def get(self, key):
          """Returns the value of key in cache"""
          return self.redis.get(key)
  
      def set(self, key, value):
          """Sets key to value in cache"""
          # backward compatibility (Redis v2.2)
          self.redis.setnx(key, value)
          self.redis.expire(key, self.ttl)
  
subject: Add docstrings to lib/cache.py and pep8 mods