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 only the elements common to both sets.
  
  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, 4}, {1, 2, 3, 4}) == {1, 2, 3, 4}
  assert intersection(set(), {1, 2, 3}) == set()
  assert intersection({1, 2, 3}, set()) == set()
output: def intersection(set1, set2):
      return set1 & set2