>> from itertools import izip_longest

>> input_list = xrange(27)
>> data_to_process = izip_longest(*[iter(input_list)]*2)
>> print list(data_to_process)
>> [(0, 1),
 (2, 3),
 (4, 5),
 (6, 7),
 (8, 9),
 (10, 11),
 (12, 13),
 (14, 15),
 (16, 17),
 (18, 19),
 (20, 21),
 (22, 23),
 (24, 25),
 (26, None)]