package java.util;
import org.checkerframework.checker.lock.qual.*;
public abstract class AbstractQueue<E extends Object> extends AbstractCollection<E> implements Queue<E> {
protected AbstractQueue() {}
public boolean add(E a1) { throw new RuntimeException("skeleton method"); }
public E remove() { throw new RuntimeException("skeleton method"); }
public E element() { throw new RuntimeException("skeleton method"); }
public void clear() { throw new RuntimeException("skeleton method"); }
public boolean addAll(Collection<? extends E> a1) { throw new RuntimeException("skeleton method"); }
// public abstract boolean isEmpty(@GuardSatisfied AbstractQueue<E> this);
}