### Question:
LightUGraph implements UGraph<L>, FastWalkable<L, UNode<L>> { @Override public boolean connected(L from, L to) { for(UNode<L> a : nodes(from)) for(UNode<L> b : nodes(to)) if(a.connected(b)) return true; return false; } LightUGraph();  LightUGraph(int capacity); @Override int size(); @Override long numLinks(); @Override UNode<L> node(L label); @Override Collection<? extends UNode<L>> nodes(L label); @Override List<? extends UNode<L>> nodes(); @Override Iterable<? extends ULink<L>> links(); @Override UNode<L> add(L label); @Override Set<L> labels(); @Override boolean connected(L from, L to); @Override long state(); String toString(); void compact(int margin); void sort(); static LightUGraph<L> copy(Graph<L> graph); @Override int hashCode(); boolean equals(Object other); @Override UNode<L> get(int i); @SuppressWarnings("unchecked") @Override Class<? extends UGraph<L>> level(); @Override List<UNode<L>> neighborsFast(Node<L> node); static final int NEIGHBOR_CAPACITY; }### Answer:
@Test public void testConnected() { UGraph<String> graph = new LightUGraph<String>(); UNode<String> a = graph.add("a"), b = graph.add("b"), c = graph.add("c"); a.connect(b); a.connect(c); assertTrue(a.connected(b)); assertFalse(a.connected(a)); assertTrue(b.connected(a)); assertTrue(a.connected(c)); assertTrue(c.connected(a)); assertFalse(b.connected(c)); assertFalse(c.connected(b)); }