input: Write a python function to find common elements in two lists.
  assert commonElements([1, 2, 3], [3, 4, 5]) == [3]
  assert commonElements([2, 3, 5, 7, 8], [3, 5, 7, 9, 10]) == [3, 5, 7]
  assert commonElements([10, 20, 30], [20, 30, 40]) == [20, 30]
output: def commonElements(list1, list2):
      return list(set(list1) & set(list2))