sub Prioritise_requests {

  my ($input_directory, $node) = @_;

  my %files;
  $files{1} = $input_directory."1";
  $files{2} = $input_directory."2";
  $files{3} = $input_directory,"3";

  # this is looping on the directories in a prioritized manner
  foreach (sort keys %files) {
        open(*DATA,$_) or die;
        # this is looping through each file you want in each directory
        foreach (sort grep(/^Flat_file.*\.txt$/,readdir(DATA))) {
                # do your stuff for each file
        }
        close(DATA);
  }
}