input: Write a function to optimize the given Python program by reducing its complexity. The input is a list of numbers, and the program prints each number on a new line. If the given list is empty, then return an empty string.
  assert optimize_printing([1, 2, 3, 4, 5, 6]) == '1\n2\n3\n4\n5\n6'
  assert optimize_printing([]) == ''
output: def optimize_printing(numbers):
      if not numbers:
          return ''
      return '\n'.join(map(str, numbers))