sub record_check {
  my( $nhf, $record)= @_; 
  my $member = $record->first_child('ID')->text;

  if ( $member <1000 ) {
    $nhf->flush();
    print "\n";
  }
  $nhf->purge();
}

my $nhf= XML::Twig->new( twig_roots => { RECORD => 1, },twig_handlers => { RECORD => \&record_check,}, );
$nhf->parsefile( $input_file );
$nhf->purge;