sub process_branch {
   # this sub is infinitely recursive - it calls itself sometimes!
   local $branch = $_[0];

   if (ref $branch eq 'SCALAR') {
      crapout("All branches must end in a piece of sub code, not a SCALAR\n$global->{breadcrumbs}");
   } elsif (ref $branch eq 'ARRAY') {
      crapout("All branches must end in a piece of sub code, not an ARRAY\n$global->{breadcrumbs}");
   } elsif (ref $branch eq 'HASH') {
      foreach my $nextbranch (keys %{$branch}) {
         # process special keywords
         if ($nextbranch eq 'directory') {                     # look for a single directory here
            my @dirs = list_of_dirs_here($global->{thisdirfull});
            if (@dirs > 1) {                                   # is there more than one directory here?
               crapout("Invalid tree structure defined.\nYou specified a single directory at $global->{thisdir}\nbut there is more than one directory here\+nPerhaps use foreachdir?");
            } elsif (@dirs == 0) {
               crapout("Invalid tree structure defined.\nYou specified a single directory at $global->{thisdir}\nbut there are no directories here");
            } else {
               $global->{breadcrumbs} .= " -> directory ($dirs[0])";
               $global->{thisdirfull} .= "/$dirs[0]";
               $global->{thisdir} = $dirs[0];
               printlog("*=====Traversing: $global->{breadcrumbs}\n");
               process_branch($branch->{$nextbranch});
            }
         } else {
            # no keywords - process regular
            $global->{breadcrumbs} .= " -> $nextbranch";
            $global->{thisdirfull} .= "/$nextbranch";
            $global->{thisdir} = $nextbranch;

            if (!-e "$global->{thisdirfull}" || !-d "$global->{thisdirfull}") {
               crapout("The directory $global->{thisdirfull}\ndoesn't exist or is not a directory");
            }

            printlog("**====Traversing: $global->{breadcrumbs}\n");
            process_branch($branch->{$nextbranch});
         }
      }
   } elsif (ref $branch eq 'GLOB') {
      crapout("All branches must end in a piece of sub code, not a GLOB\n$global->{breadcrumbs}");
   } elsif (ref $branch eq 'REF') {
      crapout("All branches must end in a piece of sub code, not a REF\n$global->{breadcrumbs}");
   } elsif (ref $branch eq 'CODE') {
      debug("Preparing to execute the code at\nbranch: $global->{breadcrumbs}\ncurrent directory: $global->{thisdirfull}") if $global->{debug};
      $branch->();
   } else {
      crapout("All tree branches must end in a piece of sub code, not values.\nThe $global->{breadcrumbs} branch ends with the value $branch");
   }
}