input: Write a function to optimize the provided Python program that prints each number in a given list on a new line. The function should return the optimized code as a string. The input list is always non-empty and contains only integers. If the given list is empty then return an error message.
  assert optimize_print_numbers([1, 2, 3, 4, 5, 6]) == "numbers = [1, 2, 3, 4, 5, 6]\nprint(*numbers, sep='\\n')"
  assert optimize_print_numbers([]) == "Error: The input list is empty."
output: def optimize_print_numbers(numbers):
      if not numbers:
          return "Error: The input list is empty."
      return f"numbers = {numbers}\nprint(*numbers, sep='\\n')"