#       This implements the logical recursion that we use to 
#       cheat the order find() imposes; 

##</code><code>##

    `preprocess'
       The value should be a code reference. This code reference is used to
       preprocess a directory; it is called after readdir() but before the
       loop that calls the wanted() function. It is called with a list of
       strings and is expected to return a list of strings. The code can be
       used to sort the strings alphabetically, numerically, or to filter
       out directory entries based on their name alone.

##</code><code>##

  ... preprocess => sub { sort { -d $a <=> -d $b } @_ }, ...