SafeCharIterator(CharacterIterator base) 
{
            this.base = base;
            this.rangeStart = base.getBeginIndex();
            this.rangeLimit = base.getEndIndex();
            this.currentIndex = base.getIndex();
}

 public Object clone() 
{
            SafeCharIterator copy = null;
            try {
                copy = (SafeCharIterator) super.clone();
            }
            catch(CloneNotSupportedException e) {
                throw new Error("Clone not supported: " + e);
            }
            CharacterIterator copyOfBase = (CharacterIterator) base.clone();
            copy.base = copyOfBase;
            return copy;
}

 public char current() 
{
            if (currentIndex <  rangeStart || currentIndex  >= rangeLimit) {
                return DONE;
            }
            else {
                return base.setIndex(currentIndex);
            }
}

 public char first() 
{
            return setIndex(rangeStart);
}

 public int getBeginIndex() 
{
            return rangeStart;
}

 public int getEndIndex() 
{
            return rangeLimit;
}

 public int getIndex() 
{
            return currentIndex;
}

 public char last() 
{
            return setIndex(rangeLimit - 1);
}

 public char next() 
{
            currentIndex++;
            if (currentIndex  >= rangeLimit) {
                currentIndex = rangeLimit;
                return DONE;
            }
            else {
                return base.setIndex(currentIndex);
            }
}

 public char previous() 
{
            currentIndex--;
            if (currentIndex <  rangeStart) {
                currentIndex = rangeStart;
                return DONE;
            }
            else {
                return base.setIndex(currentIndex);
            }
}

 public char setIndex(int i) 
{
            if (i <  rangeStart || i  > rangeLimit) {
                throw new IllegalArgumentException("Invalid position");
            }
            currentIndex = i;
            return current();
}