How do I add another loop to my nested loop

[greenpine]

Thanks for your suggestions,
perfringo, I am not sure what do you mean, as I am new to Python, and as ndc85430 suggested, I am not sure about that either, as you mentioned variable foff is only defined in else
perhaps if I define the foff, then I get errors to define the rto and rfrom variables.

If anyone can help to make it work, I appreciate it.