input: Write a function to optimize the given Python program that prints each element of a list with a newline separator using the `print` function. If the input list is empty, it should not print anything. The function should accept a list of numbers as input and return the optimized result.
  
  assert optimize_print_list([1, 2, 3, 4, 5, 6]) == '1\n2\n3\n4\n5\n6'
  assert optimize_print_list([]) == ''
output: def optimize_print_list(numbers):
      if not numbers:
          return ''
      return '\n'.join(map(str, numbers))