input: Write a function to get the intersection of two lists.
  assert get_intersection([1, 2, 3, 4], [3, 4, 5, 6])==[3,4]
  assert get_intersection([10, 20, 30], [20, 40, 60])==[20]
  assert get_intersection([1, 2, 3], [4, 5, 6])==[]
output: def get_intersection(list1, list2):
      return list(set(list1) & set(list2))