input: Write a function to find the intersection of two sets of integers. The function should take two sets as input and return a set containing the common elements of those sets.
  
  def intersection(set1, set2):
     return set1 & set2
  
  assert intersection({1, 2, 3, 4}, {3, 4, 5, 6})=={3, 4}
  assert intersection({4, 5, 6}, {1, 2, 3})==set()
  assert intersection({1, 2, 3, 4, 5}, {3, 4, 5, 6, 7})=={3, 4, 5}
  assert intersection(set(), {1, 2, 3})==set()
  assert intersection({1, 2, 3}, set())==set()
output: def intersection(set1, set2):
     return set1 & set2