### Question:
DoublyLinkedList { public boolean isEmpty() { return start == null; } DoublyLinkedList(); boolean isEmpty(); int getSize(); synchronized void insert(Monom val, boolean deleteImmediately); void display();  }### Answer:
@Test public void isEmpty() { DoublyLinkedList linkedList = new DoublyLinkedList(); assert (linkedList.isEmpty()); linkedList.insert(new Monom(5, 100)); assert (!linkedList.isEmpty()); }