Could you please explain further. If you could give an example or image to illustrate, that would be great!

So you want the result to show like the first table? Total = Previous Total + Debit - Credit

You do as following:

...
->pipe(new CalculatedColumn(array(
    "debit_minus_credit"=>"{debit} - {credit}"
)))
->pipe(new AccumulativeColumn(array(
    "total"=>"debit_minus_credit"
)))
->pipe(new RemoveColumn(array(
    "debit_minus_credit"
)))
...

What above code will do is that it created a temporary debit_minus_credit column then it use the Accumulative Column to accumulate that temporarily column as save to column total. At the end we use RemoveColumn process to remove the temporary debit_minus_credit column.

Note: Assume that you have two columns with name debit and credit

Awesome :)