input: Write a function to find the intersection of two sets of integers, and return the intersection as a new set. If either set is empty, return an empty set.
  assert intersection({1, 2, 3, 4}, {3, 4, 5, 6})=={3, 4}
  assert intersection({1, 2, 3}, {4, 5, 6})==set()
  assert intersection({1, 2, 3}, {})==set()
  assert intersection({}, {4, 5, 6})==set()
  assert intersection({}, {})==set()
output: def intersection(set1, set2):
      if not set1 or not set2:
          return set()
      return set1.intersection(set2)