public interface Iterator{
public boolean hasNext();
public Object next();
}

interface Set{
public boolean isEmpty();
public int size();
public boolean contains(Object obj);
public boolean equals(Set that);
public boolean containsAll(Set that);

public void clear();
public void add(Object obj);
public void remove(Object obj);
public void addAll(Set that);
public void removeAll(Set that);
public void retainAll(Set that);
}



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问题：
Implement the interfaces (Iterator and Set)
注意不要用Import java的method 要自己把程序写出来 ！ 在线等答案