Same comments as before applies also here. Unfortunately the previous case was easier, since the ```at(key)``` call was protected by a previous ```if (find(key))```, which guarantees that the key is in the map. After a quick look at the code here I do not see such a protection. I'd therefore urge the original author of the code, or anyone more knowledgeable than me on the real content of the code, to please assess if the ```at(key)``` choice is safe or not.