input: Write a function to find the intersection of two lists.
  assert intersection([1, 2, 3, 4], [3, 4, 5, 6]) == [3, 4]
  assert intersection([7, 8, 9], [8, 9, 10]) == [8, 9]
  assert intersection([11, 12, 13], [13, 14, 15]) == [13]
output: def intersection(lst1, lst2):
      return list(set(lst1) & set(lst2))