multimap.put("foo", 1);
    multimap.put("bar", 2);
    multimap.put("foo", 3);
    assertEquals(ImmutableSet.of(1, 3), multimap.get("foo"));
  }

  public void testCreateFromIllegalSizes() {
    assertThrows(IllegalArgumentException.class, () -> LinkedHashMultimap.create(-20, 15));

    assertThrows(IllegalArgumentException.class, () -> LinkedHashMultimap.create(20, -15));
  }