use Bio::DB::EUtilities;

my @ids = qw(CAB02640 EAS10332 YP_250808 NP_623143 P41007);

my $factory = Bio::DB::EUtilities->new(-eutil => ‘efetch‘,
                                       -db      => ‘protein‘,
                                       -id      => \@ids,
                                       -email   => ‘mymail@foo.bar‘,
                                       -rettype => ‘gi‘);

my @gis = split(m{\n},$factory->get_Response->content);

print join(‘,‘,@gis), "\n";