input: Write a function that takes two sets of integers as input and outputs the intersection of those sets. If either set is empty, the function should 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())==set()
  assert intersection(set(), {4, 5, 6})==set()
  assert intersection(set(), set())==set()
output: def intersection(set1, set2):
      if not set1 or not set2:
          return set()
      return set1 & set2