input: Write a function that constructs a nested loop in Python to print out the elements from multiple lists, with each combination of elements from the lists printed on a new line. The function should take in a list of lists and use a nested loop to iterate through each combination of elements from the lists.
  
  def print_nested_elements(lists):
      for x in lists[0]:
          for y in lists[1]:
              for z in lists[2]:
                  print(x, y, z)
  
  assert print_nested_elements([[1,2,3], [4,5,6], [7,8,9]]) # Output: prints the combinations (1 4 7, 1 4 8, 1 4 9, etc.)
output: def print_nested_elements(lists):
      for x in lists[0]:
          for y in lists[1]:
              for z in lists[2]:
                  print(x, y, z)