Excel formula to detect if a row is visible or hidden

A number of times over the years I've been looking for a way to tell if a cell in Excel is on a row that is hidden without having to resort to VBA.  Now that I've found it it seems blindingly obvious.  I share it here just in case someone else might not have seen it.

    A   B                                                                                  



1 1


2      =IF(SUBTOTAL(109,A1)=1,"Visible","Hidden")


 
If row 1 is visible B2 will display "Visible" otherwise it will display "Hidden".
 
Now I just need to wait until the need arises again before I get to use it.  I can't remember what I was doing or why I needed it but I'm sure it'll come up again!