input: Write a python function to generate a list of even numbers within a given range.
  assert even_number_list(1, 10) == [2, 4, 6, 8, 10]
  assert even_number_list(3, 15) == [4, 6, 8, 10, 12, 14]
  assert even_number_list(10, 20) == [10, 12, 14, 16, 18, 20]
output: def even_number_list(start, end):
      return [num for num in range(start, end + 1) if num % 2 == 0]