@Test public void hash3() 
{

    Node x1 = NodeFactoryExtra.parseNode("<lex>") ;
    Node x2 = NodeFactoryExtra.parseNode("'lex'") ;
    Node x3 = NodeFactoryExtra.parseNode("_:lex") ;
    assertNotEquals(hash(x1), hash(x2)) ;
    assertNotEquals(hash(x2), hash(x3)) ;
    assertNotEquals(hash(x3), hash(x1)) ;
}