Given two lists of closed intervals, each list of intervals is pairwise disjoint and in sorted order. Find the difference (non-overlapping intervals) between the two lists.
A: [1,5], [7, 10]
B: [2,6], [10,10]
result: [1,1] [6,6] [7,9]
就是 https://leetcode.com/problems/interval-list-intersections/ 变种