each_slice.py

import itertools
def each_slice(iterable, n):
    for i, item in itertools.groupby(enumerate(iterable), lambda x: x[0] // n):
        yield (x[1] for x in item)
        
for x in each_slice(range(10), 3):
    print(tuple(x))

"""output
(0, 1, 2)
(3, 4, 5)
(6, 7, 8)
(9,)
"""