@Test
public void expand_1() {

    PrefixMapI prefixes = create();
    prefixes.add(pref1, "http://example.net/ns#");
    String x = PrefixLib.expand(prefixes, "pref1:abc");
    assertEquals("http://example.net/ns#abc", x);
    String x2 = PrefixLib.expand(prefixes, "pref1z:abc");
    assertNull(x2);
}