# This code is just for illustration, as it will not run because it's dependent
# on numpy, copy, time and random.
# Counter 'pop_i' was initially under the try-clause, after the function-call
# 'msq.write_row(res_tmp[0], row_i=pop_i)'. Then it got increased even if the
# function called raised an ValueError. By moving the 'pop_i' increase to
# the finally clause, the expected result was produced.

    msq = MSquare(cl)
    res_bck = copy.deepcopy(res)
    res_tmp = []
    pop_i = 0
    while pop_i < cl:
        res_tmp.insert(0, res.pop(rnd.randint(0,len(res)-1)))
        work_ok = True
        try:
            msq.write_row(res_tmp[0], row_i=pop_i)
            # pop_i += 1
        except:
            work_ok = False
            res.extend(res_tmp)
            res_tmp = []
            msq.arr.fill(0)
            pop_i = 0
        finally:
            if not work_ok:
                pass
            else:
                pop_i += 1