I just did this recently to work around a bug (enhancement?) in a vendor's API. By some coincidence, I'd looked at "Programming Pearls" and tried this exercise

I just did this recently to work around a bug (enhancement?) in a vendor's API. By some coincidence, I'd looked at "Programming Pearls" and tried this exercise and got it wrong. My mistake was moving the left/right (beginning/end, whatever) to one more/less than the target location. At least I have plenty of company.