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