range.py

In [1]: from itertools import zip_longest

In [2]: size = 500

In [3]: parts = 16

In [4]: ranges = list(range(0, size, size // parts))                                                                                                                                                                                                                            

In [5]: ranges
Out[5]: 
[0,
 31,
 62,
 93,
 124,
 155,
 186,
 217,
 248,
 279,
 310,
 341,
 372,
 403,
 434,
 465,
 496]

In [6]: list(zip_longest(ranges, ranges[1:], fillvalue=""))
Out[6]: 
[(0, 31),
 (31, 62),
 (62, 93),
 (93, 124),
 (124, 155),
 (155, 186),
 (186, 217),
 (217, 248),
 (248, 279),
 (279, 310),
 (310, 341),
 (341, 372),
 (372, 403),
 (403, 434),
 (434, 465),
 (465, 496),
 (496, '')]