### Question:
Keys implements ElementTo.Any { @SuppressWarnings("PMD.ShortMethodName") public static Keys of(org.apache.tinkerpop.gremlin.object.structure.Element element) { return of(element.getClass()); }  @SuppressWarnings("PMD.ShortMethodName") static Keys of(org.apache.tinkerpop.gremlin.object.structure.Element element); @Override GraphTraversal<Element, Object> apply(GraphTraversal<Element, Element> traversal);  }### Answer:
@Test public void testKeysTraversal() { Keys keys = Keys.of(sanFrancisco); when(traversal.values(anyVararg())).thenReturn(traversal); traverse(keys); verify(traversal, times(1)).values("name"); verify(traversal, times(1)).dedup(); assertEquals(City.class, keys.elementType()); }