Given an Iterator class interface with methods: next() and hasNext(), design and implement a PeekingIterator that support the peek() operation – it essentially peek() at the element that will be returned by the next call to next().

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// Java Iterator interface reference:
// https://docs.oracle.com/javase/8/docs/api/java/util/Iterator.html
public class PeekingIterator implements Iterator<T> {
    private T next;
    private Iterator<T> iter;

	public PeekingIterator(Iterator<T> iterator) {
	    // initialize any member here.
	    iter = iterator;
	    next = iter.hasNext() ? iter.next() : null;
	}

    // Returns the next element in the iteration without advancing the iterator.
	public T peek() {
        return next;
	}

	// hasNext() and next() should behave the same as in the Iterator interface.
	// Override them if needed.
	@Override
	public T next() {
	    int result = next;
	    next = iter.hasNext() ? iter.next() : null;
	    return result;
	}

	@Override
	public boolean hasNext() {
	    return next != null || iter.hasNext();
	}
}