input: Write a python function to return a list of even numbers up to a given number.
  assert get_even_numbers(10) == [0, 2, 4, 6, 8, 10]
  assert get_even_numbers(15) == [0, 2, 4, 6, 8, 10, 12, 14]
  assert get_even_numbers(0) == [0]
output: def get_even_numbers(n):
      return [i for i in range(n + 1) if i % 2 == 0]