issue-18: all tests passing
issue-18: all tests passing

GraphKit/GraphKit-swift,CosmicMind/Graph,GraphKit/GraphKit-swift,GraphKit/swift,GraphKit/GraphKit,adamdahan/GraphKit,GraphKit/GraphKit,CosmicMind/Graph,NinjaIshere/GKGraphKit,adamdahan/GraphKit,CosmicMind/GraphKit,CosmicMind/GraphKit,GraphKit/swift