docs: def get_content(self, key):
          """
          Gets given content from the cache.
  
          Usage::
  
              >>> cache = Cache()
              >>> cache.add_content(John="Doe", Luke="Skywalker")
              True
              >>> cache.get_content("Luke")
              'Skywalker'
  
          :param key: Content to retrieve.
          :type key: object
          :return: Content.
          :rtype: object
          """
  
          LOGGER.debug("> Retrieving '{0}' content from the cache.".format(self.__class__.__name__, key))
  
          return self.get(key)