code: def test_combination_sum(self):
      candidates1 = [2, 3, 6, 7]
      target1 = 7
      answer1 = [[2, 2, 3], [7]]
      self.assertEqual(combination_sum(candidates1, target1), answer1)
  
      candidates2 = [2, 3, 5]
      target2 = 8
      answer2 = [[2, 2, 2, 2], [2, 3, 3], [3, 5]]
      self.assertEqual(combination_sum(candidates2, target2), answer2)
  
imports: from algorithms.backtrack import add_operators, permute_iter, anagram, array_sum_combinations, unique_array_sum_combinations, combination_sum, get_factors, recursive_get_factors, find_words, generate_abbreviations, generate_parenthesis_v1, generate_parenthesis_v2, letter_combinations, palindromic_substrings, pattern_match, permute_unique, permute, permute_recursive, subsets_unique, subsets, subsets_v2
  import unittest
label_desc: Use image node_id 2 for calling the TestCombinationSum obj's underlying member method code with example usage: obj.test_combination_sum() without return types