open my $fh, '>', $filename
    or die "Couldn't create '$filename': $!";
binmode $fh;

$browser = LWP::UserAgent->new();
my $resp = $browser->get($url,':content_cb' => sub {
    my($data, $resp) = @_;
    print $fh $data;
    return;
  },':read_size_hint' => 1024);

close $fh;