input: Write a python function to find common elements between two lists.
  assert commonElements([1, 2, 3, 4], [3, 4, 5, 6]) == [3, 4]
  assert commonElements(['a', 'b', 'c'], ['d', 'c', 'e']) == ['c']
  assert commonElements([1, 2, 3], [4, 5, 6]) == []
output: def commonElements(list1, list2):
      return list(set(list1) & set(list2))