code: private boolean isUbique(String id, RelType context)
  	{
  		if (context == null) return this.context.containsKey(id);
  
  		if (!isUbique(id)) return false;
  
  		RelType ctx = this.context.get(id);
  		return ctx == null || ctx.equals(context);
  	}
docs: Checks if the given ID is blacklisted in the given context.