csvbase process subs before checking for debt and credit fields populated

[GreenShadowMaker]

One of my banks CSV using credit and debit columns had a 0 in the alternate column instead of the required blank

moving the 'subs' to be happen before being checked for empty field, appeared to be the easiest and most flexible

sub used in combination with this:
subs = {
"^0$": "", # remove 0 value if only character
}

I imagine there is a way to do both credit/debit sub without the nearly duplicate lines, but I'm not aware.