sub func1 {
  my $file_manager = File::Manipulator->new($filename);
  $file_manager->write_line(...);
  # maybe other writes ...
  $file_manager->move_line($from_position, $to_position);
  func2($file_manager);
  func3($file_manager);
  $file_manager->move_line($from_position2, $to_position2);
}