### Question:
WSCXMLKnowledgeBase implements HierarchicalKnowledgeBase, Serializable { @Override public Instance getInstance(String id) { return instanceID.get(id); } WSCXMLKnowledgeBase(InputStream xmlTaxonomyStream);  WSCXMLKnowledgeBase(String xmlTaxonomy);  WSCXMLKnowledgeBase(File xmlTaxonomyFile);  WSCXMLKnowledgeBase(); @Override Concept getConcept(String id); @Override Instance getInstance(String id); @Override Set<Concept> getSubclasses(Concept concept); @Override Set<Concept> getSuperclasses(Concept concept); boolean equivalent(Concept x, Concept y); boolean isSubclass(Concept x, Concept y); boolean isSuperclass(Concept x, Concept y); @Override Concept resolveInstance(Instance instance); Set<Instance> getInstances(Concept concept); Set<Concept> getConcepts(); Set<Instance> getInstances();  }### Answer:
@Test public void testGetInstance(){ assertNotNull(this.kb.getInstance("inst1426393654")); assertNull(this.kb.getInstance("con2025477491")); }