code: public int compareTo(Key<K> o) {
  		if(o != null) {
  			if (o.time > time) {
  				return -1;
  			}
  			else if (o.time < time) {
  				return 1;
  			}
  			else if(o.key != null) {
  				return o.key.compareTo(key);
  			}
  			else {
  				return 0;
  			}
  		}
  		
  		return 0;
  	}
docs: /*
  (non-Javadoc)
  
  @see java.lang.Comparable#compareTo(java.lang.Object)