input: Write a function to create a nested loop in Python that prints out the elements from each list in separate lines. The function should accept a list of lists as input. 
  
  def nested_print(lists):
      for x in lists[0]:
          for y in lists[1]:
              for z in lists[2]:
                  print(x, y, z)
  
  assert nested_print([[1,2,3], [4,5,6], [7,8,9]])==None
  
  Expected output:
  1 4 7
  1 4 8
  1 4 9
  1 5 7
  1 5 8
  1 5 9
  1 6 7
  1 6 8
  1 6 9
  2 4 7
  2 4 8
  2 4 9
  2 5 7
  2 5 8
  2 5 9
  2 6 7
  2 6 8
  2 6 9
  3 4 7
  3 4 8
  3 4 9
  3 5 7
  3 5 8
  3 5 9
  3 6 7
  3 6 8
  3 6 9
output: def nested_print(lists):
      for x in lists[0]:
          for y in lists[1]:
              for z in lists[2]:
                  print(x, y, z)