### Question:
LinkedStack implements Stack<E> { @Override public E pop() { return null; }  static void main(String[] args); @Override int size(); @Override boolean isEmpty(); @Override void push(E e); @Override E top(); @Override E pop();  }### Answer:
@Test void testPop() { LinkedStack<Integer> s = new LinkedStack<>(); for(int i = 0; i < 10; ++i) s.push(i); assertEquals(9, s.pop()); assertEquals(9, s.size()); }