if (exists($data->{channel}->{title})) {
 $mydata=$data->{channel}->{item};
 my $data->{channel}->{item}->[0]=$mydata;
 print "Only one item is present"; 
}
if ($data->{channel}->{item}->[$y]) {
 while (($data->{channel}->{item}->[$y])&&($y>-1)) {
  $keyword=$data->{channel}->{item}->[$y]->{epfl_keywords};
  ...