* Implement the function that merges two binary search trees
Merge overlappong intervals: [(13, 19), (15, 26), (17, 27), (18, 18), (19, 21), (22, 28), (31, 35), (32, 36), (33, 42), (41, 54)] [(9, 20), (13, 13), (22, 29), (23, 30), (27, 35), (33, 40), (44, 48), (44, 53), (45, 48), (45, 57)]