How to use the Bioperl to parse the parse flat file of UniProtKB database in order to get the function annotation of a protein ?

now, I can only fetch out the all comment of a protein, can someone help me ? I only want to fetch out the "FUNCTION".

my code :

#!/usr/bin/perl
use warnings;
use Bio::SeqIO;
use Bio::DB::SwissProt;

open (GENE, $ARGV[0]) or die "cannot open gene file:$!";
$db_obj = Bio::DB::SwissProt->new;

my  @genes;
while(<GENE>){
    chomp;
    push @genes, $_;
}

$stream_seq = $db_obj->get_Stream_by_acc(["@genes"]);

my $i=0; 
while ( my $seq_obj = $stream_seq->next_seq )
{
 my $anno_collection = $seq_obj->annotation;
for my $key ( $anno_collection->get_all_annotation_keys ) 
{
my @annotations = $anno_collection->get_Annotations($key);
                for my $value ( @annotations ) 
{
              if ($value->tagname eq "comment") {
       print  "$genes[$i]:",$value->display_text,"\n";                          
           }                                      
    }
}
$i++;
}

result:

Q8N349:-!- FUNCTION: Odorant receptor (Potential).
-!- SUBCELLULAR LOCATION: Cell membrane; Multi-pass membrane protein.
-!- SIMILARITY: Belongs to the G-protein coupled receptor 1 family.
-!- WEB RESOURCE: Name=Human Olfactory Receptor Data Exploratorium
    (HORDE);
    URL="http://bip.weizmann.ac.il/cgi-bin/HORDE/showGene.pl?key=symbol&value=OR2L13";
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