$ perl test.pl
0,1,3,4,5,"# +1 +2 keep"
1,3,1,4,5,"# +2 -2 keep"
2,2,3,3,4,"#  0  0 keep"
1,0,0,4,5,"# -1  0 keep"
0,4,8,4,5,"# +4 +4 keep weird pyhton"
0,5,10,,5,"# +5 +5 keep"
$