code: def test_merge(self):
      interval_list = [[1, 3], [2, 6], [8, 10], [15, 18]]
      intervals = [Interval(i[0], i[1]) for i in interval_list]
      merged_intervals = Interval.merge(intervals)
      self.assertEqual(
          merged_intervals,
          [Interval(1, 6), Interval(8, 10), Interval(15, 18)],
      )
  
imports: from algorithms.arrays import delete_nth, delete_nth_naive, flatten_iter, flatten, garage, josephus, longest_non_repeat_v1, longest_non_repeat_v2, get_longest_non_repeat_v1, get_longest_non_repeat_v2, Interval, merge_intervals, missing_ranges, move_zeros, plus_one_v1, plus_one_v2, plus_one_v3, rotate_v1, rotate_v2, rotate_v3, summarize_ranges, three_sum, two_sum, max_ones_index, trimmean, top_1, limit, n_sum
  import unittest
label_desc: Use image node_id 1 for calling the TestMergeInterval obj's underlying member method code with example usage: obj.test_merge() without return types