input: Write a python function to print all integers from 1 to a given number.
  assert print_numbers(5) == "1\n2\n3\n4\n5\n"
  assert print_numbers(3) == "1\n2\n3\n"
  assert print_numbers(0) == ""
output: def print_numbers(n):
      return '\n'.join(str(i) for i in range(1, n + 1)) + ('\n' if n > 0 else '')