input: Write a python function to find the intersection of two lists.
  assert intersection([1, 2, 3, 4], [2, 4, 6, 7]) == [2, 4]
  assert intersection([10, 20, 30], [10, 40, 50]) == [10]
  assert intersection([5, 15, 25], [35, 45, 55]) == []
output: def intersection(list1, list2):
      return [item for item in list1 if item in list2]