@Test
void testContainsSimpleValue() {

    MultiMap<String> mm = new MultiMap<>();
    mm.putValues("food", "apple", "cherry", "raspberry");
    mm.put("color", "red");
    mm.putValues("amount", "bushel", "pint");
    assertTrue(mm.containsSimpleValue("red"));
    assertFalse(mm.containsValue("nutrition"));
}