input: def unionList(list1: List[int], list2: List[int]) -> List[int]:
      """ Given two lists of integers, return a list that contains all unique elements present in either of the two lists.
      >>> unionList([1, 2, 3, 4, 5], [3, 4, 5, 6, 7])
      [1, 2, 3, 4, 5, 6, 7]
      """
output:     set1 = set(list1)
      set2 = set(list2)
      return list(set1.union(set2))