input: Write a function that takes a list of numbers from 1 to 8 and prints their cubic values. If the list is empty, the function should print an empty line.
  assert print_cubics([1, 2, 3, 4, 5, 6, 7, 8])==None
  assert print_cubics([])==None
output: def print_cubics(numbers):
      if not numbers:
          print()
      else:
          for num in numbers:
              print(num ** 3)