input: Write a function to print out the elements from three nested lists in a new line using a nested loop. The function should take three lists as input and use three nested loops to print each combination of elements from the lists. If any of the lists is empty, the function should print "Input lists cannot be empty."
  assert nested_lists_print([[1,2,3], [4,5,6], [7,8,9]])==None
  assert nested_lists_print([[1,2], [3,4], [5,6,7]])==None
  assert nested_lists_print([[], [4,5,6], [7,8,9]])=='Input lists cannot be empty.'
  assert nested_lists_print([[1,2,3], [], [7,8,9]])=='Input lists cannot be empty.'
  assert nested_lists_print([[1,2,3], [4,5,6], []])=='Input lists cannot be empty.'
output: def nested_lists_print(list1, list2, list3):
      if not list1 or not list2 or not list3:
          print("Input lists cannot be empty.")
          return
      for i in list1:
          for j in list2:
              for k in list3:
                  print(i, j, k)