input: Write a python function to return the last n elements from a list.
  assert last_n_numbers([1, 2, 3, 4, 5, 6, 7, 8, 9, 10], 3) == [8, 9, 10]
  assert last_n_numbers([10, 20, 30, 40, 50], 2) == [40, 50]
  assert last_n_numbers([5, 15, 25, 35, 45], 4) == [15, 25, 35, 45]
output: def last_n_numbers(lst, n):
      return lst[-n:]