input: 
  def intersection(set1, set2): 
      return set1 & set2
  
  # Example usage:
  # >>> intersection({1, 2, 3, 4}, {3, 4, 5, 6})
  # {3, 4}
  
output:     result = set()
      for item in set1:
          if item in set2:
              result.add(item)
      return result