Fixes:

1. Lambda Function

   >>> arr_list = [[1, 4], [3, 3], [5, 7]]
   >>> sorted_list = sorted(arr_list, key=lambda x: x[1])
   >>> sorted_list
   [[3, 3], [1, 4], [5, 7]]
   

2. Sliding windows

   >>> from itertools import islice
   >>> def slide(list_name, window_size):
   ...           z = [islice(list_name, i, None) for i in range(window_size)]
   ...           return zip(*z)