Folder.getFiles Multiple Filters Mask

Hi all,

Folder.getFiles (".*") ... in this case it will get all types of files

Folder.getFiles (".jpg") ... in this case it will get all files with .jpg extension

... but how can I filter to get (for example) all files with ".jpg", " .tif" or ".eps" extension ?

ESTK help says: A mask string can also be the name of a function that takes a File or Folder object as its argument. It is called for each file or folder found in the search; if it returns true, the object is added to the return array.

Any idea of how to make such a function?

I will appreciate any help.