/**
* Given a nested list of integers, implement an iterator to flatten it.
*
* Each element is either an integer, or a list -- whose elements may also be
* integers or other lists.
*
* Example 1:
* Given the list [[1,1],2,[1,1]],
*
* By calling next repeatedly until hasNext returns false, the order of elements
* returned by next should be: [1,1,2,1,1].
*
* Example 2:
* Given the list [1,[4,[6]]],
*
* By calling next repeatedly until hasNext returns false, the order of elements
* returned by next should be: [1,4,6].
*
*/
/**
* // This is the interface that allows for creating nested lists.
* // You should not implement it, or speculate about its implementation
* public interface NestedInteger {
*
* // @return true if this NestedInteger holds a single integer, rather than a nested list.
* public boolean isInteger();
*
* // @return the single integer that this NestedInteger holds, if it holds a single integer
* // Return null if this NestedInteger holds a nested list
* public Integer getInteger();
*
* // @return the nested list that this NestedInteger holds, if it holds a nested list
* // Return null if this NestedInteger holds a single integer
* public List