code: public boolean containsKey(Object key) {
  		// the key is a direct hit from our cache
  		if(cache.containsKey(key))
  			return true;
  		// the key is a direct hit from our hashmap
  		if(container.containsKey(key))
  			return true;
  
  		// check if the requested key is a matching string of a regex key from our container
  		Iterator<String> regexKeys = container.keySet().iterator();
  		while(regexKeys.hasNext()) {
  			if(Pattern.matches(regexKeys.next(), (String) key))
  				return true;
  		}
  		
  		// if the three previous tests yield no result, the key does not exist
  		return false;
  	}
docs: checks whether the cache or container contain a specific key, then evaluates the
  container's keys as regexes and checks whether they match the specific key.