input: Write a python function to return a list of the first 20 even numbers from 0 to 40.
  assert get_even_numbers() == [0, 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, 22, 24, 26, 28, 30, 32, 34, 36, 38]
  assert get_even_numbers()[:5] == [0, 2, 4, 6, 8]
  assert get_even_numbers()[-5:] == [28, 30, 32, 34, 36, 38]
output: def get_even_numbers():
      return [i for i in range(0, 40) if i % 2 == 0]