sub Prioritise_requests {
  
  my ($input_directory, $node) = @_;
  
  my $input_directory_lowest = $input_directory."1";
  my $input_directory_middle = $input_directory."2";
  my $input_directory_highest = $input_directory."3";
  
  
  my @lowest_priority;
  my @sorted_lowest_priority;

  
  my @middle_priority;
  my @sorted_middle_priority;
  
  
  my @highest_priority;
  my @sorted_highest_priority;
  
  opendir (LOWEST, "$input_directory_lowest") or die "Error opening directory: $!";
  
  foreach (sort grep(/^Flat_file.*\.txt$/,readdir(LOWEST)))
    {
      
      push @lowest_priority, $_;
      
    }
   @sorted_lowest_priority = sort { -M $a <=> -M $b } @lowest_priority;
  closedir *LOWEST;
  
  
  my $request_of_interest = 'none';
  
  
  
  opendir (MIDDLE, "$input_directory_middle") or die "Error opening directory: $!";
  foreach (sort grep(/^Flat_file.*\.txt$/,readdir(MIDDLE)))
    {
      
      push @middle_priority,$_;
     
      
    }
   @sorted_middle_priority = sort { -M $a <=> -M $b } @middle_priority;
  closedir MIDDLE;
  
    
  
  opendir (HIGHEST, "$input_directory_highest") or die "Error opening directory: $!";
  foreach (sort grep(/^Flat_file.*\.txt$/,readdir(HIGHEST)))
    {
      
      push @highest_priority,$_;
     
      
    }
   @sorted_highest_priority = sort { -M $a <=> -M $b } @highest_priority;
  closedir HIGHEST;
  
  
  if (@sorted_highest_priority) {
    foreach (@sorted_highest_priority){   # foreach high priority request
      $request_of_interest = $_;
      
      my $do_I_pick_up_request =  Is_the_file_mine($node, $request_of_interest);
      
      if ($do_I_pick_up_request eq 'Y'){
	my $time_to_run = Do_I_run_the_request_now ($request_of_interest);
	if ($time_to_run eq 'Now'){
	  move "$input_directory_highest/$request_of_interest", "$input_directory" or warn $!;
	  return;
	}
      }
    }
  }
  if (@sorted_middle_priority) {
    foreach (@sorted_middle_priority){  
      $request_of_interest = $_;
      #return  $request_of_interest;
      
      my $do_I_pick_up_request =  Is_the_file_mine($node, $request_of_interest);
	
      if ($do_I_pick_up_request eq 'Y'){
	my $time_to_run = Do_I_run_the_request_now ($request_of_interest);
	if ($time_to_run eq 'Now'){
	  move "$input_directory_middle/$request_of_interest", "$input_directory" or warn $!;
	  return;
	}
      }
    }
  }
  
  if (@sorted_lowest_priority) {
    foreach (@sorted_lowest_priority){  
      $request_of_interest = $_;
	
	my $do_I_pick_up_request =  Is_the_file_mine($node, $request_of_interest);
	
	if ($do_I_pick_up_request eq 'Y'){ 
	  #return  $request_of_interest;
	  
	  if ($do_I_pick_up_request eq 'Y'){
	    my $time_to_run = Do_I_run_the_request_now ($request_of_interest);
	    if ($time_to_run eq 'Now'){
	      move "$input_directory_lowest/$request_of_interest", "$input_directory" or warn $!;
	      return;
	    }
	  }
	}
    }
  }
}