input: Write a function to calculate the intersection of two sets of integers and return the intersection as a set. If any of the input sets is empty, return an empty set.
  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}, {})==set()
  assert intersection({}, {3, 4, 5, 6})==set()
  assert intersection({1, 2, 3, 4}, {5, 6, 7, 8})==set()
output: def intersection(set1, set2): 
     if not set1 or not set2:
        return set()
     return set1 & set2