input: Write a function to construct a nested loop in Python that prints out the elements in a new line when given a list of lists. The function should iterate through each element of the lists and print them in the order they appear. If the input list is empty, the function should return an empty list.
  
  assert nested_loops([[1,2,3], [4,5,6], [7,8,9]]) == None
  assert nested_loops([]) == []
output: def nested_loops(lst):
      if not lst:
          return []
      for sublist in lst:
          for element in sublist:
              print(element)