>The comment you replied to was talking both about the negatives of hidden allocations and about purity That is incorrect. The comment was requesting that `Add

>The comment you replied to was talking both about the negatives of hidden allocations and about purity That is incorrect. The comment was requesting that `Add::add(String, &str) -> String` should be impled by creating a new String instead of mutating an existing one. My comment pointed out why this request was meaningless.