input: Write a python function to find common elements in two sets.
  assert find_common({1, 2, 3}, {3, 4, 5}) == [3]
  assert find_common({'a', 'b', 'c'}, {'b', 'd', 'e'}) == ['b']
  assert find_common({1, 1, 2, 2}, {2, 3, 4}) == [2]
output: def find_common(set1, set2):
      return list(set1.intersection(set2))