input: Write a function to find common elements between two sets.
  assert find_common_elements({1, 2, 3}, {3, 4, 5}) == [3]
  assert find_common_elements({10, 20, 30}, {20, 40, 50}) == [20]
  assert find_common_elements({'a', 'b', 'c'}, {'c', 'd', 'e'}) == ['c']
output: def find_common_elements(set1, set2):
      return list(set1 & set2)