// Copied from org.eclipse.ocl.examples.test.xtext.PivotDocumentationExamples.java

		Library library = getLibrary();  // get library from a hypothetical source

		OCLHelper helper = ocl.createOCLHelper(EXTLibraryPackage.Literals.LIBRARY);

		// use the constraints defined in the OCL document

		// use the getBooks() additional operation to find a book
		ExpressionInOCL query = helper.createQuery(
		    "getBooks('Bleak House')->asSequence()->first()");

		Value bookValue = ocl.evaluate(library, query);
		Book book = (Book) bookValue.asObject();
		System.out.printf("Got book: %s%n", book);

		// use the unique_title constraint to validate the book
		boolean isValid = ocl.check(book, constraintMap.get("unique_title"));
		System.out.printf("Validate book: %b%n", isValid);	
