<SYSTEM_TASK:>
Solve the following problem using Python, implementing the functions described below, one line at a time
<END_TASK>
<USER_TASK:>
Description:
 def slice_by_size(seq, size):
 """Slice a sequence into chunks, return as a generation of chunks with `size`."""

    filling = null
    for it in zip(*(itertools_chain(seq, [filling] * size),) * size):
        if filling in it:
            it = tuple(i for i in it if i is not filling)
        if it:
            yield it