input: Write a function to construct a nested loop in Python to print out the elements in a new line when given a list of lists as input. The function should iterate through each list by nesting loops one inside the other, including the innermost loop to print the elements in the form of x, y, z.
  assert nested_loop([1,2,3], [4,5,6], [7,8,9])==True
  assert nested_loop([10,20], [30,40], [50,60])==True
  assert nested_loop([1], [2], [3])==True
  assert nested_loop([0,0], [0,0], [0,0])==True
  assert nested_loop([], [], [])==True
output: def nested_loop(*lists):
      for lst in lists:
          for elem in lst:
              print(elem)