}
		if lc.Len() > 20 {
			t.Fatalf("length should be less than 20")
		}
	}

	if lc.Len() != 10 {
		t.Fatalf("length differs from expected")
	}
}

func TestLRUConcurrency(t *testing.T) {
	lc := lru.NewLRU[string, string](0, nil, 0)
	wg := sync.WaitGroup{}
	wg.Add(1000)
	for i := 0; i < 1000; i++ {
		go func(i int) {