fetching exons with ensembl

#!/usr/bin/perl

use strict;
use warnings;

use Bio::EnsEMBL::ApiVersion;
use Bio::EnsEMBL::Registry;

my $ac = shift;

my $r = 'Bio::EnsEMBL::Registry';
$r->load_registry_from_db(
      -user => 'anonymous',
      -host => 'ensembldb.ensembl.org',
      -port => 5306
     );

my $ta = $r->get_adaptor( 'homo_sapiens', 'Core', 'Transcript' );

my ($tx) = @{ $ta->fetch_all_by_external_name($ac) };

printf("Ensembl %s (%s; %s)\n", software_version(), $ac, $tx->display_id);
foreach my $exon ( @{ $tx->get_all_Exons() } ) {
  printf("%d\t%d\t%d\n", $exon->start, $exon->end, $exon->length);
}