input: Write a function to optimize the given Python program that prints each element of a list on a new line. The function should take a list of numbers as input and return a string representation of the numbers, each on a new line. If the input list is empty, it should return an empty string.
  assert optimize_print_program([1, 2, 3, 4, 5, 6])=='1\n2\n3\n4\n5\n6'
  assert optimize_print_program([])==''
output: def optimize_print_program(numbers):
      return '\n'.join(map(str, numbers)) if numbers else ''