APIs and LibrariesPremium EpisodesS2 Premium Episode #044: #one? Avdi Grimm January 9, 2013 0 Comments Somtetimes you need to know if exactly one element in a collection has a given property. For that situation, we have the #one? predicate method. This page is just for members. Sign in or subscribe to gain access! Username Password * Remember Me Forgot Password Related CategoriesAPIs and Libraries, Premium Episodes, S2 PremiumTagscontainers, corelib, Enumerable & Enumerator