### Question:
MultifacetTopsySearcher extends AbstractMultifacetSearcher<WebContent> { static String extractIdentifier(String permalink) { if (StringUtils.isNotEmpty(permalink)) { Matcher matcher = URL_STATUS_PATTERN.matcher(permalink); if (matcher.find()) { return matcher.group(1); } } return null; } MultifacetTopsySearcher(String apiKey);  MultifacetTopsySearcher(Configuration configuration); @Override String getName(); @Override SearchResults<WebContent> search(MultifacetQuery query); @Override boolean isDeprecated(); static final String CONFIG_API_KEY; static final String SEARCHER_NAME; }### Answer:
@Test public void testExtractIdentifier() { String identifier = MultifacetTopsySearcher .extractIdentifier("http: assertEquals("407136819797450752", identifier); }