input: Write a function to find the union of two lists and return it as a set.
  assert unionList([1, 2, 3, 4, 5], [3, 4, 5, 6, 7]) == {1, 2, 3, 4, 5, 6, 7}
  assert unionList([10, 20, 30], [30, 40, 50]) == {10, 20, 30, 40, 50}
  assert unionList([1, 1, 1], [2, 2, 2]) == {1, 2}
output: def unionList(list1, list2):
      return set(list1).union(set(list2))