### Question:
IndexResultSet extends TreeSet<IndexItem> { public IndexItem get(String uri) {return uriToItem.get(uri);}  boolean contains(String uri); boolean contains(IndexItem item); @Override boolean contains(Object o); IndexItem get(String uri); IndexItem get(IndexItem item); @Override boolean add(IndexItem item); @Synchronized boolean remove(IndexItem item); @Override @Synchronized boolean remove(Object o); @Override boolean removeAll(Collection<?> c); @Override void clear(); @Override boolean addAll(Collection<? extends IndexItem> c); boolean retainAll(Collection<?> c); @Override Iterator<IndexItem> iterator();  }### Answer:
@Test public void testGetString() { IndexResultSet test = testSet(); assertNotNull(test.get(LEIPZIG_URI)); assertNull(test.get(BERLIN_URI)); }
@Test public void testGetIndexItem() { IndexResultSet test = testSet(); assertNotNull(test.get(leipzig2)); assertNull(test.get(berlin)); }