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

		// create an OCL helper object
		OCLHelper helper = ocl.createOCLHelper(EXTLibraryPackage.Literals.LIBRARY);

		ExpressionInOCL invariant = helper.createInvariant(
		    "books->forAll(b1, b2 | b1 <> b2 implies b1.title <> b2.title)");
		   
		ExpressionInOCL query = helper.createQuery(
		    "books->collect(b : Book | b.category)->asSet()");
