getChain     :: (Graph g) => g a b -> Node -> NGroup
getChain g n = n : unfoldr (chainLink g) (chainNext g n)
getChain     :: (Graph g) => g a b -> Node -> NGroup
getChain g n = n : unfoldr (chainLink g) (chainNext g n)
getChain g n = n : unfoldr (chainLink g) (chainNext g n)