input: Write a function to find the intersection of two sets of integers. If either of the sets is empty, return an empty set. If the intersection is not empty, return the elements that are common to both sets.
  def intersection(set1, set2):
     if not set1 or not set2:
         return set()
     return set1 & set2
  
  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}, {}) == set()
  assert intersection({}, {1, 2, 3}) == set()
  assert intersection({}, {}) == set()
output: def intersection(set1, set2):
     if not set1 or not set2:
         return set()
     return set1 & set2