What happens to unvested stock options when a public company goes private?

If a public company gets taken over by private equity investors, what is the typical handling of employee stock options ? The stock options are given as incentive, so it would be unfair to ignore them even if they are unvested. On the other hand, determining a fair value for them is difficult. Would love to hear from people who have gone through this process or have the legal expertise to comment on this situation.|||You can keep them as unissued stock or you can delete them. It all depends upon how you set the company up legally.