input: Write a python function to generate a list of numbers using an iterator.
  assert generate_numbers(1, 5) == [1, 2, 3, 4, 5]
  assert generate_numbers(10, 15) == [10, 11, 12, 13, 14, 15]
  assert generate_numbers(0, 3) == [0, 1, 2, 3]
output: def generate_numbers(start, end):
      return list(range(start, end + 1))