I have a shared workbook that is used by 10 people.

When you click on Tools/Shareworkbook it tells you who has the book open.
Is there a way I can use this data in the workbook itself?

If a user if called "JohnS", could I have a formula in A1 that says

=If(<JohnS has workbook open,"John Sharing","John Absent")

What formula do I put between "<" and ""

Many thanks