title: Time complexity of Swift's Set.indexOf
body: <p>What is the time complexity of <code>Set.indexOf</code>? The <a href="https://developer.apple.com/library/tvos/documentation/Swift/Reference/Swift_Set_Structure/index.html#//apple_ref/swift/structm/Set/s:FVs3Set7indexOfFxGSqGVs8SetIndexx__" rel="nofollow">documentation</a> doesn't say, and the <a href="https://github.com/apple/swift/blob/swift-2.2-branch/stdlib/public/core/HashedCollections.swift.gyb#L365" rel="nofollow" title="delegates">source</a> delegates to some kind of internal storage class (<code>_VariantStorage</code>/<code>_VariantSetStorage</code>) whose source I can't find.</p>