The current implementation of Q003 rule to accommodate the nested f-strings is a bit too complex. It can possibly be simplified using two loops instead of one. The outer loop is the regular token loop while the inner loop would be for the f-strings. When the outer loop encounters the FStringStart token, then the control would go to the inner loop where it would be easier to just break if it's not possible to perform the check.

This is low priority and an internal refactor for readability purpose.