input: from typing import List
  
  def union_of_lists(list1: List[int], list2: List[int]) -> List[int]:
      """
      Find the union of two lists, which means all unique elements that are present in either of the lists.
      >>> union_of_lists([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 sorted(set1.union(set2))