code: def test_merge_intervals(self):
      interval_list = [[1, 3], [2, 6], [8, 10], [15, 18]]
      merged_intervals = merge_intervals(interval_list)
      self.assertEqual(merged_intervals, [[1, 6], [8, 10], [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 2 for calling the TestMergeInterval obj's underlying member method code with example usage: obj.test_merge_intervals() without return types